Question Need some help with a mechanical keyboard problem

[Imagine13]

A friend just called me having a problem with his keyboard where the bottom row of keys does not work. The RGB's on the keyboard work.
The windows key is always litten up and the arrow keys all don't work except the "up" arrow key.
I instructed him on how to uninstall and reinstall drivers for the keyboard, but that didn't help. Also ran a keyboard troubleshooter from windows settings, didn't help either.
He seems kind of desperate so I am writing a post here.
What could be the problem? Any suggestions would help.

 

[rgd1101]

test with a new keyboard?

 

[Imagine13]

test with a new keyboard?

He had another keyboard plugged in, it worked fine. Also thank you for the suggestion.

 

[rgd1101]

then use the new, working keyboard

 

[tecmo34]

What is the keyboard? Is it a custom keyboard that he or she built like a GMMK Pro or is it a pre-built like a Corsair K70 would be helpful to know?

If a custom like a GMMK Pro, when they put the switches in they could have issues on the bottom row and bent a pin. This wouldn't impact the RGB but would cause the keys not to work.