MacBook display flickering, stripes. Help much appreciated :)

Hi guys,

Here's to hoping there's a solution I haven't tried... This morning, I opened up my laptop and suddenly the screen started flickering. Meaning: it never turns black, just same display as usual but seems to be shaking/flickering continuously, especially white areas are unbearable on the eye.

Symptoms:

- Grey horizontal lines randomly appear (as I type, two appear exactly on the spot where I'm typing)

- The apple logo seems somehow 'imprinted' on the desktop (see photos). It won't go away, not even at the log in screen. You can also detect a square and some sort of cirkel on top of it, if you look carefully.

- It gets a little less annoying when I turn down brightness.

- It seems unrelated to apps. It's unresponsive to any possible solution.

- When I connect my macbook to an external display, there is no problem at all.

What I've tried:
- Deleting Firefox (I read this could cause trouble)

- Normal reset, normal shutdown

- SMC reset

- NVPRAM reset

- Apple Diagnostics test, incl. disk utility first aid

- Running in safe mode

- Creating a new user account

- Deleting Mac OSX and reinstalling

I swear I did nothing with this laptop. I left it on the couch as I always do. It was in sleep mode. When I opened the lid, this was happening.

About the laptop:

- Macbook (Retina, 12 inch, early 2016)

- Processor 1,1 GHz intel core m3

- Memory 8 GB 1867 MHz LPDDR3

- Graphicscard Intel HD Graphics 515 1536 MB

- Serienumber C0***TJ1

Photos: