Now it's coming back to me….
From the owners manual at:
https://www.rigpix.com/bearcat/bc560xlt_manual.pdf
Memory Backup
The BC 560XLT has a built-in capacitor type memory backup. When the power switch is in the off position, the programed frequencies will be retained for up to sixty days; however, it's a good idea to keep a list of programmed frequencies.
So, I'd try plugging it in and leave it turned on for a while to make sure that capacitor is fully charged and see how it does. If that doesn't fix it, open it up and look for the big capacitor that might be leaking its creamy filling out all over the circuit board.