If you would like to reset your HTX-202 to factory settings, or if you are seeing "Er1" when powering on the
radio, hold down the "Fn" and "D" buttons while turning on the radio.  It should beep twice, and then go to
the main VFO display.

If Er1 keeps returning, or if you are having problems with saving changes, the memory backup battery needs to
be replaced.  It's a tabbed CR-2016 battery, commonly available online.  You will have to do a fair amount of
disassembly to replace the battery.