How to Unlock The Robot
This character can be unlocked in a single run, even though it may take a few tries.
Unlock Hint 1: The character requires some (re-)assembly. The good news is that you only have 1 part to find. The bad news is you will also have to find someone to do the repairs.
Unlock Hint 2: The required part always spawns, and always in the same room, as a by-product of something you might have fixed before. This is not a room you need to visit much. The person to find can also be found always, and at the same place every time, although not on the same floor as the part.
Unlock Hint 3: Have you ever tried jumping after an elevator after it leaves? You don’t get damage, but you end up in a special room.
Unlock Hint 4: The first elevator shaft you can jump in contains some junk item(s) that may be of interest (not called “junk”). You may also run into someone trying to fix the elevator there (The Tinker). To find the junk item, you need to help the Tinker once.
Unlock Hint 5: Sadly, the Tinker character only fixes elevators, and not the robot. You will need to take the part you find to a very skilled craftsman.
Unlock Hint 6: Or perhaps, a craftswoman? Like one working deep within the gungeon?
Unlock Solution: Find the Busted Television in the first elevator room at Gungeon Proper, after unlocking the first shortcut. Take it to the Blacksmith in the Forge, who will fix the robot. This is of course, a challenge, given that the item will drop with every dodge roll. You may want to consider throwing it across pits and also not picking it up before clearing the Gungeon Proper.