Sunrise Side is on to it with the hair dryer I think. Get it to where the candy melts and clean it up with a wooden stick or plastic spudger. Don't use a screwdriver or other metal object, you may damage circuit traces with that. Once you get most of it off you can use good old soap and water and a tooth brush or something similar to clean the rest up. Rinse it well, blow it off with compressed air, and that blow dryer (or set it in the sun) to dry it completely.
That's not the right battery on your MPU either. It should be a 3.6V lithium AA battery. The one installed is a 3.6V lithium 1/2AA which will only last about 1/2 as long as the AA. If I recall correctly my S6000 batteries lasted about two years roughly, so you'll be changing it every year if you stick with the 1/2AA. I also recommend getting a through hole AA battery holder and solder it on the board. Then you won't need to do any soldering the next time it goes dead. Here's a pic, it's a Gamemaker MPU board, but the same idea.
Also using a pair of tweezers or something similar peel as much of the gaming tape off that you can. Be careful around the original labels on the chips, they like to peel off with the tape.