Through the little Etsy store I've got, I offer Game Boy game repair mostly just so I get to "play" on different problems, and a different problem did arrive.
This Game Boy Advance game, although worked, requires a battery for the real time clock aspects of the game (i.e. timed events). The problem was that there was a repair attempt that had taken off the entire pad for the battery, and in fact had go through the pad, through the silk screen and had gone all the way into the fibre glass insulation layer (you might be able to see in the photo the woven pattern).
Before slapping a battery on and jumping the positive leg to the right component, I wanted to check that nothing else was missing. Thankfully the community have tried to preserve a lot of the history (in this case, the PCB traces) but also published it freely on the web.
From this I also found a resistor had been lost in the previous repair. I don't think it's clear from my photo, but what I did was to bond the missing resistor in a completely different location (before it traces to a capacitor) and then use a jumper wire from the replaceable battery case. This was mostly in case the battery case was torn off again it wouldn't cause damage to the components on the board.
Once that was all done, the game happily had its clock and was returned to it's owner the same day.