I was able to turn on the printer without this error. I checked it several times and it is repeatable. it is not suitable to give the printer to the client, but it can be useful for your own needs:
The display shows error 5B00 (the lamp blinks 6 times).
1. I turn the printer off
2. I press the red triangle and hold it down and press the printer on.
3. I release the triangle button, and now holding power I make this sequence:
I press the triangle (the jam indicator lights up), press the triangle (the jam indicator goes out), press the triangle again (the jam indicator lights up), press the triangle (the jam indicator goes off) then release the power button and the printer starts without error. you can print on it, enter the menu etc. Everything indicates that the printer is operational.
The problem occurs when the printer is turned off. the printer will not turn on for the second time. you have to pull the plug out of the socket, wait a moment, then it will turn on but with this error. If I turn it off now and repeat the procedure, the printer will be fully functional again.
Now the challenge is to keep this state. I will be grateful for any ideas. I unscrew the printer and clean the "pampers" and see what happens. I do not see any sensors here but it can help.