Samsung F2380 on and off when connected to PC (Hdmi or vga)

Hello, I hope someone can point me in the right direction

I got a Samsung F2380 the other day (could not find it in the list here, sorry),
it seemed to work fine, but now it's been going on and off with an horizontal white blitz for half a second, it does it every 5 seconds.

It was working fine one night, until the laptop went in stand by maybe, not sure if that was the trigger. It doesn't do it if disconnected from the pc, it does it on two different computers. I tried to use different cables and ports.. hdmi, vga, with and without adapters. I have no idea what the problem can be.

It worked again fine for some hours yesterday, not sure how the switch on sequence might be different than usual.

Even the menu works weird, sometimes it comes up, sometimes it doesn't, I was trying to reset the monitor, but no luck. For some reasons it had stopped doing it after I disabled it from the device manager and reinstalled the driver, no idea which sequence was successful though, but then again it lasted only a few hours.

It had stopped also after I was playing with the menu a bit, then restarted going on and off. It doesn't actually do it while I click around the menu, although the menu comes up at its own wish at times. I hate to throw away stuff that still works or needs a bit of help, but I am out of ideas with my basic knowledge.

Any clue? Is it something I might be able to fix with basic soldering knowledge?

thanks a lot!!