Restore IMEI with IMEI&SN Writer

Restore Lenovo A820's IMEI with IMEI&SN Writer

If you don't understand something or have any doubts don't do it, I take no responsibility for relaying my experience here. This is taken from my much longer post Driver Sanity in Windows, Restoring IMEI to Lenovo A820 with all dead ends and fails removed. I can only support the single method tested herein.

When I get a new MTK phone, the instructions for that don't consider I might already have drivers installed. This can lead to driver conflicts. Another thing you should beware of before asking for help is that you don't have devices flagged in Device Manager. If your Device Manager looks as flat as this:

Then this isn't a problem for you and you can continue to the Out With the Old (Unseen Driver Conflicts) section.

Install Missing Manufacturer / OEM (eg Dell, HP, Acer etc) Drivers

For years I put up with an unidentified, but disabled "Simple PCI communication interface" or "Simple PCI communication controller". Only after struggling to connect my phone on a VCOM/COM port did I decide keeping this motherboard device deactivated might be a bad idea. I dug out my original factory "drivers and apps" disk and put it in the DVD drive. About 3 minutes later it loaded :)

It wasn't necessary to use the manufacturer's installer. I activated the offending hardware from device manager and either uninstalled it first or just showed it to my DVD drive (more on this process in just a moment, it is this process that is the crux of this document). Windows very efficiently installed just the driver and none of the bloat, it was a minor device I might have lived without.

Out With the Old (Unseen Driver Conflicts)

Consider the following where Lenovo Composite ADB Interface is in some way undesirable:

 

 
You may have previous installations cached allowing Windows to automagickly reinstall the device. Every time this happens repeat the above procedure to arrive at a "clean" installation w.r.t. this particular driver.

I stress this is only for third party drivers, things Windows or your OEM may have preinstalled, may be harder to find better/correct drivers for.

When Window's cache of drivers is empty it will either either ask you for one or list it in Device Manager with an exclamation mark nest to it. Job done.

Restoring IMEI

You'll notice in previous screenshots the "Ports (COM & LPT)" entry is displayed in Device Manager. The problem with my VCOM driver was that, initially, it was only fleetingly visible the instant a connection was made with the powered down phone. Device Manager would flicker, display the entry for a second, then flicker again removing all mention of "Ports (COM & LPT)". You have just a second to right click an offending driver. Once right clicked the clock stops and you can carefully click uninstall. Then tab away and check the instructions. If you have to open the "Ports (COM & LPT)" you'll almost certainly miss it and get frustrated fast. If you have something else there, that's one less click you need in that second. That's why my "Ports (COM & LPT)" is visible, a modem or (old) printer can be used for this purpose.

This driver is essential for META mode to connect your phone with the low level MTK tools. The correct driver will maintain an entry in "Ports (COM & LPT)" all the while the phone is connected in META mode. My driver, from previous ROM upgrades and subsequent phone purchases proved incorrect.

To be sure of any driver's provenance you must uninstall all previous drivers as outlined in the Out With the Old (Unseen Driver Conflicts) section above. To know when Windows is ready for the correct driver watch for an exclamation mark on the entry, in the case of this particular device the entry will read, "MT65xx Preloader".

At this point you can install the new driver(s). The file I was given was DriverInstall_v5.14.53_WinXP_Win7.exe,

MD5: aefe6fc53400b8f9a313cbacd4a4f50b,
SHA1: 2f12e07f5785defb81e9f8ab7e501b5d951c8c0f

published my MediaTek. When I go to install it Windows warns that the publisher is unknown. Continue as any other installation. When you are asked (in red!) to install an unsigned driver, go for it, four times! I think this is just MediaTek being cheap not getting MicroSoft to sign and test their drivers. MicroSoft's high false positive rate causes users to blithely dismiss all sorts of security warnings. I don't guarantee these drivers, I use them as do many others.

I'd actually just dismissed exactly four of these warnings installing for my other phone's ROM, with an entirely different installer, a script, so I "knew" what was happening. It would install the unsigned drivers first then install the signed ones over the top. Often signed drivers don't work so I was happy  to try unsigned.

With just these drivers installed they should be sufficient to enter META mode. I'd never before been asked to install four consecutive unsigned drivers in a row, MLais publish a how-to telling me to do this, so now I do.

ADB Drivers

I believe my old VCOM driver was being supplied by the SP_Driver_v1.x pack and causing incompatibility. I can't describe how to install these and ADB drivers here, that is outside the scope of this article. Approved drivers are:

sp_drivers_v1.5_lenovo.zip:

MD5: 2e9d1ca627056703f471f2bbe1b199ea
SHA1: 79bbc822e6af5d394ccabe229a8a2640bf146848

I instead used SP_Drivers_EXE_v1.6 from Pakyto's "RESTAURAR IMEI.zip"

MD5: 0be4b2fb53c18d9bc392e5e4cc6f6972
SHA1: d483be492df8785efe00b4416e5f7ba9229895e8

Software Sources

I didn't ultimately use Pakyto's apdb_modemdb_A820 because the name of his Modem Database included P780 instead of A820.

(from Pakyto)
BPLGUInfoCustomAppSrcP_MT6589_S00_P780_V23

MD5: 0f244cd43a65b9aee65a31b73cbcc00c
SHA1: c6a5a4102c77fbb2493323bc7c9ae9f458a506a7

APDB_MT6589_S01_MAIN2.1_W10.24

MD5: 80a45a9bb5bd5416692901de6974d871
SHA1: 76638fb9cd4234437a5c64f149134b9cb81bcae8

The following are more A820 specific:

(from https://yadi.sk/d/ylJyJbDjZWm7k, from http://www.mcrf.ru/forum/archive/index.php/t-36527.html)
apdb_modemdb_A820.7z

MD5: f770b3e08a5ec076b592493b38591d44
SHA1: 062578a596b90d05b1cf6a2c37bff324740cc3d6

BPLGUInfoCustomAppSrcP_MT6589_S00_A820_V16

MD5: f5a6a5a28ee227533ccb41c35e7155db
SHA1: 8d41e8d604cc9c4a750b7eb9305f641746d2691f

APDB_MT6589_S01_MAIN2.1_W10.24

MD5: 80a45a9bb5bd5416692901de6974d871
SHA1: 76638fb9cd4234437a5c64f149134b9cb81bcae8

 from somewhere I found:

imei&sn writer v1.5.3.rar

MD5: 52f43ae9e73b2279493977ad4f9b68ac
SHA1: f15224419dd9bc440bc006ff53d5efef53fefed5

which contains the 2012 tool IMEI&SN Writer.exe

IMEI&SN Writer

It reported a success when I just flashed the IMEI:

Success, but I was too tired to remember to what extent. In any case it wasn't acceptable so I repeated with all the fields filled in and it fixed it.

For step 3, Select DB, use the files described above in Software Sources, or google "apdb_modemdb_A820" and see my checksums. Or try the following (verified).

IMEI&SN Writer V1.5.3.7z (3.25Mb)
MD5: 955fc522fd47376e6f7e3c6e3b1b9fc0
SHA1: dd6e0c0a80a57502c6d8fe2436dd6fc6a19e8798

apdb_modemdb_A820_20150729.7z (5.34Mb)
MD5: 6e6ee6541b5800e8386da1ba7436a9da
SHA1: e80700159bc31ba2d94cdfbfeb351b023e581e2f

Lenovo A820 Teardown

Follow this guide if you're worried about replacing your screen or something.

Remove tight rear cover to expose six screws, shown in yellow, the middle right one had a protective 's' security sticker over it.

Don't try and separate the plastics, the separation is performed at the screen junction with the black plastic. The screen is plastic but heavy and transparent. Slide a finger nail in somewhere and slowly work it around, hearing a click as each catch pops.

You are greeted with the backs of two PCBs. I've tip-exed out my identifying codes. The bottom PCB can be prised off but is connected at its top edge by some flat cable connector I didn't proceed to investigate further, there was little electronics of interest there and the PCB itself is paper thin.

The top PCB is much thicker and held in place by 2 very loose and obvious screws and three cable connectors.

This shows the connectors undone. Use soft plastic like a toothpick. The top one has a catch opposite the cable that flicks up. The aerial connector at the bottom left is removed with by pulling with your finger nails. The bottom right one lifts straight up. You will need to lever the PCB out of its housing. A plastic blade would be ideal, again the toothpick and metal blade would do in a pinch.

After breaking the friction with the casing movement stops after a few mm. Their is no connector for the volume rocker. The volume rocker is flexible and must be prised from the casing using a sharp knife to break the adhesive. A few mm more and some tape is found to connect a heatsink / shield on the opposite face to the SIM connectors to another "silver box" remaining with the screen part of the phone. If I had a cracked screen I should have looked further. It's very sticky tape and I removed more than I would have liked. There is one more hidden connection. Use a toothpick to prise it from the PCB as you pull it up. The connection is to the flat cable running along the battery compartment to the mic and screen connections.

This is the new face the PCB reveals, when almost completely detached (vestiges of tape remain).

On the other side of the tape are more markings.

And finally the chips, in case we're compiling our own Android and want more details.

The MediaTek markings were obscured by a pink heat sink sponge thing and this made photographing difficult. I should have tried harder to read but this is my best photo, and with reference to others I believe the markings are (lines are duplicated where there is doubt):

MEDIATEK
ARM                    APM
MT6589 W MT6589 WVK MT6589 WMK
1309-ATA 1309-ATAH
DTNFU?29 DTNFU

As usual assembly is the reverse of removal. I used a smooth plasic spatula, yeah, a toothpick, to help reattach most of the very sticky silver tape. I also wedged it under the hidden connector to increase its reactive force as I pressed the PCB down on to it.