First, get the model ID and CID to get the correct firmware. In order to do it, turn on the LENOVO TAB 2 A8 in the bootloader mode and read all information according to the instructions.
You may also check the model ID by entering the IMEI number on IMEI.info
Once you have model ID and CID, go to Motorola Firmware and select the appropriate model. Then, choose the latest software version(must have the same CID, downgrade not allowed until you not have bootloader unlocked).
After downloading the software, unpack it using any file archiver and copy all the content of the folder into c:\mfastboot where all necessary tools have already been unpacked.
Changing firmware in the phone will erase all of your data.
All described operations you are doing at your own risk.
If want saves your data do a backup before start.