This appears to be a common problem here. Blades run, headlights on, etc. Turned out be the drive motor. Eric at Ryobi service desk the best. Anyway thought this beeper code chart helps with troubleshooting. Good luck.
Mine beeps 4 times, won’t move either. Called Ryobi, said it is a defective GUAGE! Ok. Sending me a guage. For the life of me I don’t see how that is the problem. Been a couple weeks, no gauge. Will check back After replaced.