Lo batt flashing on inverter.

[Yachts]

I put coach away last Saturday morn. Turned off master 12 volt flipped breakers for fridge and tvs down by inverter. Turned off inverter. And turned off coach batteries in battery bay. Returned Friday morn for the weekend trip and chassis batteries were dead. Turned on coach batteries in bay and inverter. Coach batteries were strong. Started genset but my merge switch was not working.. Jumped the chassis batteries to the coach batteries with cables and charged everything up.. Everything is working fine. Except inverter has a lo battery flashing in small letters in the upper left hand corner of the display.. If everything is showing good voltage and working fine why the lo battery display? Lease help.