I have a proformzt5 that has worked great. However, one day the screen seems to be in demo mode, and as soon as I put the safety key in, the screen darks out and it beeps at me every time I press a button. I've reset the reed switch, checked connections, and tried holding the start/speed up keys but no luck. Suggestions?

Exercise & Fitness - Proform - ZT5 Treadmill