Unplug the machine, place the machine on a counter on top of a towel. Clean everything you can access.
Turn the machine on its side and take off the bottom. Clean all the lint.Check the reverse button area. Is there lint? Put a stocking over a vacuum cleaner and clean....Don't forget your pedal. Sometimes lint in the pedal can cause electrical issues with your machine. To check this, borrow a pedal from a friend or dealer to see if that is the problem. Plug your machine into a surge protector and check to see if it is still going in reverse. Make sure you have the plug plugged in correctly. It sounds like reverse polarized plug. I know these ideas are diverse and many different suggestions, hopefully, one of these "checks" will work.
Best wishes in your quest for a fix.