Monitor image problem after a power failure

[Ambiguous64]

I'm getting some strange colouring (see vertical lines in the photo) on my 2nd monitor after a recent power outage. It's an old AOC 2236, and running off my onboard gpu. I also have my main display running off a GTX 1060. 

It displays most colours fine, but it seems to be missing some of the darker colours and instead just shows off colour lines. 
So far I have tried deleting the onboard drivers and reinstalling. I tried deleting the AOC monitor drivers and reinstalling. I switched it to the other graphics card port which runs my main monitor (which is fine) and it still has these problems. I'm fairly certain is a monitor issue and not software now, though it did seem to correct itself for a time earlier.

Any suggestions on anything that may be the cause, and a possible solution? So far I'm thinking either the monitor's psu, or maybe the cable connecting it to the gpu. Also what do I call this kind of problem? Half the battle is in trying to describe it. 

[TechyBen]

Swap cables/inputs. Does it still persist? Might have been a power spike when the power went out, and damaged the display.

 

To know if it is the display or the internal graphics (intel or AMD?) swap the inputs and see if the problem persists.

[Ambiguous64]

Unfortunately I don't have a spare cable or I'd try it. The onboard is Intel 4600. Also, it's started flicking off and on occasionally. 

[Ambiguous64]

Further developments, it will sometimes correct itself, and then other times I get the black and white now. It seems to help if it has been switched off for sometime, so perhaps a heat problem?