I'd start by wiggling the outside casing to try and see where it's attached to the frame of the machine and take out any screws holding it down, using a little dish or some folded up tin foil to hold all the screws of one type, then slap on a lil masking tape on that bowl, label it A, then another bit of tape on the part it came off, or near the holes they came from, and label those A, and then B for the next part, etc., all the while trying to free the casing that holds the on off switch.

Don't disassemble more than ya have to. Another poster said they found teardown videos for devices of this make, I'd watch through those a few times to see if any of em get to the switch you're trying to fix beforehand, so you got a better idea of what to expect and maybe you can minimize the amount of work you have to do to get it at it.

Take it slow and steady, there's no rush. Anything that can be assembled can be disassembled.

After you're done with the switch, might as well do a little cleaning/maintenance:

1. the brush is held in by the blue piece with two tabs - push those tabs up, take off the guard and you can remove the brush. Use scissors to cut any hair wrapped around the brush and remove it then pull as much junk out as you can. The brush has one square peg end that the motor drives and it'll need to go back in the correct side, the other side just sits in and then put the blue piece back on.

2. the wheel that spins around in different directions is how the vacuum controls its movements and it can be pulled out and cleaned of all that hair and junk - your robot will be better able to maneuver and understand where it is.

3. You may want to consider some replacement parts for where I see a missing side brush, for example: https://www.amazon.com/CauYien-Replacement-RoboVac-Cleaner-11s/dp/B0BYRWQRPK/ref=asc_df_B0BYRWQRPK

You got this and you'll feel better once you've done it yourself!