i search a gp32 nlu or flu LCD Screen or broken gp32

Verical lines might come from a broken LCD, a broken LCD cable, a broken LCD connector, broken pins on the VRAM*, or something more esoteric on the main board.

But yeah, another unit with different failure modes is probably the best way to identify and fix this issue with the least outlay.

* I don't know the GP32 hardware that well, so I dunno if it's got anything you could actually describe as VRAM or not.