Panel Low Battery usually indicates that your panel battery needs to be recharged promptly. 

Troubleshooting Panel Low Battery Issues

1. If your home's power has gone out, allow 24 hours for the battery to recharge. If a low battery persists, continue troubleshooting.
2. Verify that the transformer (Plug) is still properly secured in outlet.
3. Verify that the outlet has power.
4. Verify that the outlet is not a GFCI (Reset button outlet) or switch-controlled outlet.
5. Inspect power wire for any damage.
6. Verify a proper connection on the screw terminals for the transformer.