How do I fix my monitor?

I plugged in a powerbank via USB into my laptop. And the monitor (aswell as the usb port) stopped working. The laptop itself runs smoothly however using an external monitor. I had it looked at and I've been told there may be something wrong with the motherboard (they were 85% sure) and it needs to be replaced. But it'll cost €700!

I came up with the idea to buy a portable/ bigger external monitor for €200 euro and hook it up via HDMI. Which is a pretty good idea. This one: https://www.amazon.co.uk/dp/B013XFJKGI/r...

But they said the laptop monitor still works, it's just the motherboard that has the problem.

So, are there any recommendations on what I should do? I'd rather not spend too much money. I'm willing to do it myself.

The laptop camera works fine and the logo doesn't light up, the other sockets work fine, as well as the keyboard which does light up