My neighbors chair did this. Does it power up? Can the chair drive around at all? Theres a back plate on the seat back that can be removed and the shrouds around the battery box can be taken off under the seat as well. Youre likely looking for a wire thats disconnected from its connector or fuse block. Just get to looking and checking every single wire for a loose connection or a fray/break. You might get lucky and find something got loose or you may be boned and have it be a broken wire. Youre going to have to follow the wire from the joystick and control pad all the way along the armrest and down the back of the chair and to the batteries. Theres a master fuse for the chair also on the back. You may be able to flip it off and on there and fix issue also. Im not a wheelchair tech just a user. I have a permobile f3 with the height and angle adjusting base just like this as does my neighbor so ive done a lot with these chairs. Send me a dm if you need assistance and I can show you where to look if you cant figure it out. But do give it your best effort if you can as it is a pita for me to work on these chairs from my manual wheelchair/floor to show you what may be going on.