Lenovo A850 Flash To Stock ROM and Repair IMEI (Change IMEI)

Flashing Stock ROM to Lenovo A850.
1. Download SP Flash Tool (Smart Phone Flash Tool) from AndroidXDA.
2. Download Lenovo A850 Stock Rom from AndroidXDA. Link 1, Link 2.
3. When you download "Lenovo_A850_4.2_(by_xdafirmware.com).zip" from AndroidXDA, it already included Flash Tool (SP Flash Tool) version 3.1344. You can use it OR download later version, no problem.

4. Extract "Lenovo_A850_4.2_(by_xdafirmware.com).zip".
5. Goto extracted folder, open folder "Driver", install one for your PC.

6. Restart PC.
7. Power-off your phone. Connect one end of the USB cable to PC. And for the other one, when you want to connect to the phone, connect the USB cable to phone WHILE HOLDING VOLUME UP BUTTON to enter phone factory mode. If you hold the volume down button when connecting to PC, then your phone will enter meta mode.
8. Wait until driver installation is finished.
9. Goto folder "Flash Tool" and run Flash_tool.exe.

10. Select scatter-loading button and select mt6582_android_scatter.txt.

11. Checked the checkbox for DA DL All With Check Sum. This one important. I have try download without checked this checkbox, and I got error message on Lenovo start up logo. Press the Download button after you checked the checkbox.

12. Wait until downloading finished until there's Download OK green circle message appear. Power-on the phone. Wait until it go to start screen.

Repair IMEI (Unknown/Null IMEI) After Flashing Stock ROM.
1. First, open the back cover of your phone, write down the IMEI on a piece of paper.
2. After you have successfully download/flash the stock ROM for Lenovo A850, open Google Play app.
3. Search and download/install Mobileuncle Tools.
4. Launch the Mobileuncle Tools app.
5. Goto Engineer Mode --> Engineer Mode (MTK) --> Connectivity --> CDS Information --> Radio Information --> Phone 1.
6. Write AT+EGMR=1,7,"IMEI1" and press SEND AT COMMAND button.
7. Now push the Back button of your phone, select Phone 2.
8. Now write AT+EGMR=1,10,"IMEI2" and press SEND AT COMMAND button.
9. Surely you will confuse a little bit about IMEI1 and IMEI2. For IMEI1, enter the IMEI that you found at the back of your phone. For IMEI2, you plus 8 for three last number of IMEI1. For example, last IMEI if 520. Then it will be 520+8=528. If 327, then 327+8=335. More example, IMEI1 is 86415432123 (just a random number). Then, IMEI2 will be 123+8=131, IMEI2 = 86415432131.
10. Thanks to Al-Qamar tutorial for this, I've follow the tutorial with success.