OLED65E6 Screen is black in all inputs and apps, Sound OK

Hi

I have OLED65E6, it started having a weird problem in the last day or so.

Sometimes the screen would fade away and shows almost like falls in black slowly until the whole screen is fully black, sometimes picture goes black abruptly. this happens in all inputs and apps, hitting menu doesn't show anything but sound is ok and I can turn volume up and down without problem

I did factory reset and it didn't fix the issue, only turning tv off for 15+ minutes fixes the issues but happens again

when screen is working, there is not distortion or imperfection at all

TV is out of warranty, I hope it's just power board or motherboard and not panel itself. how much would it generally cost to repair it? once repaired am I good for some good time?

I appreciate your help here

Here are some of the videos that show the issue

++https://photos.app.goo.gl/3v9UbiPZN2CXuf...