70TU7125 loop start + if put tape on some FFC cable PINs then sound OK but picture HS

[Michael06]

Hi! After almost 3 years, my 70TU7125 TV is stuck in bootloop: backlight turns on then turns off with black screen and bliking LED light (randomly or 2 times successively). If i put a tape on some PINs of the FFC cable,  the TV works with sound+backlight but picture is HS (see screenshots). Any idea ? Thank you ++++