Fire stick 4k issue

[squarehead94]

Hi all. got given an old 4k fire stick. when I plug it in, it detects the device on my tv (pops up to switch to that hdmi channel) but when you go on to that hdmi channel, it doesn't do anything - tv just shows a black screen for about 5 seconds then displays a no signal input message. I've tried this on multiple TV's, tried multiple cables, with and without the HDMI extender cable, to no avail. Didn't want to throw it in the bin as was hoping there was something glaringly obvious I could try before i throw in the towel.

TIA

 

[squarehead94]

Plugged in to AC or USB?
Try plugging in to a pc monitor, same result?

tried both, same result.