For specific button combinations to enter "Download Mode" or "Recovery Mode," refer to the TCL 10L User Manual .
Perform the forced flash method with the previous stable firmware. Download an older version (e.g., V412 instead of V520) and flash via pinhole recovery. tcl t770h firmware
Mismatched firmware for your hardware revision. Fix: Redownload the correct version. Check the build string: your original version might be V8-T653T01-LF1V412 , while you tried LF1V520 . Stick to the same T653T01 platform. For specific button combinations to enter "Download Mode"