Hello, my name is Michael. I can help you with your question. If the battery was changed when there wasn't power, or if something went wrong during the change, you may have lost your programming. You can still do a reset on the register. Just be aware that you may have to program it from the start again. Here are two ways to do the reset.
1) Unplug the AC cord from the wall outlet.
2) Set the MODE switch to the (SRV ) position.
3) Plug in the AC cord to the wall outlet.
4) While holding down JOURNAL FEED key, turn to (SRV) position
from (SRV ) position.
Procedure-2 (without SRV key)
1) Turn the mode switch to the (REG) position.
2) Ensure the batteries are not installed in the battery compartment
and insert the plug into the outlet.
3) The right most decimal point will blink for a few seconds.
4) The register will sound three beeps.
5) The register will display ; L 0000