PM5 screen issues - Concept 2 Rower

[Murray1978]

Hi all,
I have had a Concept 2 Rower, PM5, for a number of years but it has barely been used in my garage gym. I am keen to get back into it so have cleaned it up but the screen rarely comes on. It has never been damaged, I have changed the battery and the cable into the monitor looks fine.
Does anyone have any suggestions as to what I can do to try and resolve the issue?
Any guidance would be greatly appreciated.
Murray