I get error code 5100

If you are using a Cannon i550, code 5100 is a carriage error, check the timing strip for contamination (plastic strip about 1/4" in width) If the unit is not homing, check for obstructions.

Just FYI:
If you need to put the printer in service mode, you can do the following:

1. hold RESUME then press & hold POWER
2. release RESUME, then press it twice, the light should go amber then green again.
3. you're now in service mode (you can release POWER now)

If you need to empty the waste tank:
I think waste tank reset is 4 presses of the RESUME button. To confirm, press POWER once.

Hope this was helpful, didn't see the printer type posted which made it harder.