This is the worst era for hacking electronics. They've got everything tucked away in microprocessors or custom chips, or a mix of both.
If you have a dab of black goop on a chip, it's most likely COB - chip on board. That's where they glue the chip to the board, bond wires from the chip to some nearby pads, and bury the whole thing under an epoxy to protect it from the environment.
This is a very cheap form of construction, and generaly the parts die after a few years from slow contamination through the board.
If you want to get started, I'd recommend browsing the net for electronics forums, maybe buying a Don Lancaster book or a book about programming little chips, like the PIC chips. Also, hackaday.com has some really fun projects.
Best Luck
Mike