[moltuae]

I used to repair TVs and monitors .... a loooong time ago. But they're pretty disposable these days. Even IF you can get hold of the service manuals, schematics and components, it'll almost always cost more in time than it's worth just to strip the thing down and rebuild it.

My guess would be some sort of video controller SMD IC has a 'dry' joint or two. You might be able to fix it if you can identify the offending IC and resolder it. If it's of the 'ball grid array' variety ('legless'), your best chance would be to 'reflow' the solder paste by carefully heating the IC, which requires a hot air gun (or sometimes putting the entire board in an oven *might* work. It might also destroy it of course if you get the timing/temperatures wrong).

Given than the fault is thermally related, probably the best way to identify the culprit would be with a can of 'freeze spray'.

My second guess would be a video controller ribbon cable connection. You could try waggling some internal cables or applying a little pressure to see if you can make the fault come and go.

If you haven't done so already, you could try Googling the model number to see if it's a common fault and whether anyone has posted an easy fix method.