I will be very detailed, advanced users should skip the boring stuff :P
This guide was writed based on this thread. A similar guide can be found at this thread. Look there for more info.
You will need:
- Rooted Lenovo A850 (simple guide here, not tested)
- Mobileuncle MTK Tools (GooglePlay)
- Recovery Image for A850 (CWM or TWRP)
BEFORE GOING ON, MIND THAT I TAKE NO RESPONSIBILITY IF ANYTHING HAPPENS ON YOUR PHONE.
USE AT YOUR OWN RISK!!
1. Download the recovery image:
First of all we need to find out what firmware version our phone has (ROW or CN).
I can see mine looking the Baseband version (located at Settings->About phone->Version Infos->Baseband version) which is "A850.ROW.v18", so i have a ROW firmware installed. I suppose it will say something like "A850.CN.vXX" if you have a CN filmware.
If you don't know which version you own, try one. If it is the wrong version, your phone will just not boot into the recovery. Reboot the phone and install an other version.
Now we can download the right recovery image version.
- For ROW firmware download this (Mirror 1 from source thread).
(This version of CWM never worked for me, scroll down at bugs)
- For CN firmware download this (Mirror 1 from source thread).
(Downloads include both CWM and TWRP recoveries)
After downloading, extract the content (use 7zip program). You will see 3 files, we will not need the "MT6582_Android_scatter.txt" file. You can delete it or keep it if you want to flash roms in the future.
2. Move the revovery image in you SD card:
Connect your phone on your PC and mount the SD card. Now move the recovery image you want in you phone's SD card:
- For TWRP is the "recovery_TWRP_126.96.36.199.img" file
- For CWM is the "recovery_z_CWM_v188.8.131.52.img" file
(You can delete the other one after that)
When the move finishes, disconnect the phone.
3. Install Mobileuncle MTK Tools:
Open GooglePlay on your phone, search for "Mobileuncle" and install Mobileuncle MTK Tools.
4. Install recovery: (IF YOU DO NOT KNOW WHAT YOU ARE DOING DO NOT PROCEED)
Open Mobileuncle MTK Tools. (You will be asked to give root permition to the app, select always yes)
Click on "Recovery Update" and the app will find the recovery image in your SD card. (in the first line, do not click any other recovery)
Click on the recovery image you selected (recovery_TWRP_184.108.40.206.img or recovery_z_CWM_v220.127.116.11.img), click OK to install recovery... wait some seconds, and then click OK to reboot into recovery.
Done! You are in the recovery
(If the phone reboots and then shutdown, the recovery.img didn't work. Try an other version.)
How to get into recovery: (2 simple ways)
- Power of your phone. Wait some second. Press the power button and bot h volume keys and not let them go until the logo appears (the phone will also vibrate). It takes up to 7 seconds to open, keep pressing the buttons until the vibration.
- With Mobileuncle MTK Tools, open it and click on "Into Recovery Mode".
- CWM: Use volume keys and the power button to move around
- TWRP: Touch the screen, swipe etc.
- linerty (from the Russian lenovo forum)
- I got an error will trying to backup (CWM ROW version), "can't mount data" . If you face this problem, better install this CWM version. It worked for me