A few screws and it came apart. The problem was easy enough to find.
Here is the Ryobi P1113 lithium battery charger.
Four torx head screws on the bottom (under the rubber feet), and it comes apart.
Finding the damage is quick and easy. Notice the little plastic chunk.
This is where it used to be.
Amazingly, the body of the transistor or whatever it is was actually intact. I could easily read the part number of TOP247YN.
So, I checked digikey and mouser for this part number. It looks like they cost almost $5 for one piece. A new aftermarket charger costs $24 shipped. So, I think I'm going to go that route instead of trying to repair it. Who knows if the rest of the components are actually all okay still.
Interestingly enough, this charger actually has a recall going on for it. Ryobi has it posted on their website. Unfortunately, my charger is a later serial number and not eligible for a replacement.
https://cc831cbd7a5a3a616f82-5093119...b758551c16.pdf