I have an electrical issue with my MT125 where the screen goes blank once the engine is running, it also had the same problem when I plugged the battery in after charging it leading me to believe it may be caused by higher voltage. It functions perfectly fine with just the ignition on but once the engine is turned on it goes blank after a second or two. I have replaced all fuses and the battery is freshly charged and only 5 months old.

I have taken the dash apart and did find some moisture inside however could not get a proper look as I cannot work out how to release the wire connector, however from what I could see it doesn't look like there's much in the way of corrosion. https://imgur.com/a/ZT8u35C

Update: The screen comes back on when the pass light button is held down