Panasonic F61 Code Error

Hi guys, My Panasonic SA UX100 sound System displays F61 code error after turning it On then switches off after a few seconds. I tried removing all the 2 speaker cables but the problem is still there.

I took it to a repair shop due to long waiting list they couldn't attend me for about two weeks . After 2 weeks the guy called to tell that my sound system is working without any repair. I took it home and played over the night but when I tried to turn it on the next morning F61 error came back.

WHAT IS THE PROBLEM PLEASE HELP