Black screen with flickering line

Hello,

I have a HISENSE TV from 2018.

When I try to turn it on, the home screen appears (Hisense) but the screen goes black with a small flickering white line. The fact that a clear and sharp image appears for a few seconds at startup makes me think that the panel is not dead.

I tried unplugging it for several minutes (even several hours), and did the same with all the cables unplugged. The same problem persists.

I checked the HDMI cable, and it works perfectly fine on another television...

What can I try to resolve the issue?