suicide battery
not such a bad idea for the manufacturer. planned obsolescence, when it dies the operator has to buy something new to replace his money maker. much easier to replace the current processor and burn 2 eproms when the battery gives out or buy the kit I have seen around for 40 dollars which has all the parts you need to get it working again. don't worry about it until the game finally dies, fixing it is well documented and a snap to do when you get the parts in.