The case of the exploding battery… this was an interesting one. MacBook Pro Mid 2015 model presented with a warped case which wouldn't close and a cracked trackpad. The battery had become so swollen it was literally bursting out of the machine.
The photos show just how large the battery had become. I replaced the battery with a considerably cheaper non-Apple certified one (couldn't be worse, right?). Amazingly the trackpad still worked. Managed to bend case back into place and she fired up just fine!