Power windows and locks stop working

I'm posting this for my brother he has an 03 GTI. It seems at random his power windows will stop working. It's happened after hitting a bump, after disconnecting the battery and just at random while driving. Both the windows and sun roof stop working. Sometimes the locks are affected as well.

Not too sure where to start, tried scanning with vagcom while they were working and didn't get any codes. Any ideas?

Disconnect battery cables and then touch them together for a few seconds and then reconnect to the battery. Worth a try.

If this happens after hitting bumps then it's probably related to a ground issue.

Could try swapping out fuse 14 too, it could be a bit dicky even if it looks ok.