This baby shark was out to get me. I see why you were having a grand old time — not a lot of room, and they solder the darn board in place (to the battery pickups). I’d pull the batteries before working on it (I didn’t and have played the song about 100 times). Plus, since the B+ is soldered at the battery pickup, you risk overheating it, unless you’re quick.
One thing I did notice is that the device’s switching circuit is extremely sensitive. Just tapping the male jack will trigger it. (Like a low tech capacitive sensor.)
I do believe the most time was spent trying to get the case screws back in place. I pulled out my handy Fun-Tak to help hold the screw (even with a magnetic screwdriver). Play Dough, Clay, etc. Anything that gives a little grip.