Thanks for guide. Had a strange error with my computer suddenly not booting and showing me strange pictures. Internet recovery did now work and after checking with another disc and read here I could order a new cable and follow this guide. Seams to be quite a common problem but kind of easy to fix as long as you get the cable. Thanks!
Had the most strange errors with a wi-fi with errors for long. Send the computer both to apple and to insurance without success.
Now I'm on my own on my wifi first broke saying "No hardware installed", Bluetooth was still working in the beginning thou. After checking here I ordered a new cable and everything was fixed in under 30 minutes.
The cable I bought was names -A in the end instead of -02 but everything works just fine so far. According to the seller they are the same. Thanks for help solving this strange problem in a simple way!