Iiyama monitor stuck in kiosk mode

[NiallF]

I just got a 55" Prolite TE5512MIS Touchscreen Monitor. I put it into kiosk mode, and it says in the manual to press input + 2580 on the remote to bring up the debug menu and disable the kiosk mode - but it doesn't do anything when I do that, it just stays in kiosk mode.The remote is working, I can increase and decrease the volume, but I can't do much else. I got in touch with their support via their website form but the customer service guy couldn't offer any advice except press input + 2580. He gave up on me eventually.