I have a Sherbourne electric riser leather chair. Unfortunately the chair doesn't rise anymore nor does the footrest work. The buttons on the handset do not work, but the white button brings the chair down, O,K. But the chair doesn't rise anymore.
Peter

P Cox, January 2022

Presumably the last successful action was when you bought the chair down "on the white button".

I wonder if the chair is plugged in properly, the wall outlet switched on,the cables are all intact and the power supply is OK.

If there's a backup battery, make sure that's OK. If I was designing a chair, I'd allow it to return to reset position but nothing more in the event if no supply and backup battery running low.

It's possible the power supply is off/disconnected/failed or otherwise not working and you've been running on backup battery.

Otherwise, I'd be closely examining cables for wear, tear, cracks (especially where cables enter housings)

Shsbsv, January 2022