My initial reaction...
Many of the devices we discuss here in fact have a little battery inside, and this battery will allow the storage of certain info. These batteries may normally last for many years, but not forever. I'd wonder if the battery in your device has failed. If it's a static cell, then it just needs replacing, this might be easy to do, but might not. If it's a rechargeable battery, just leaving the unit on for a few hours may get it working again. If the battery is totally dead, maybe it should be removed/replaced before it leaks corrosive substances over valuable components.
Geoff