I recently had a '110 with a similar issue. One check to make - log in directly to the device and go to the "Status" & "Phone & Line Status" tabs. Check the VBAT value. With the phone on-hook, it should be somewhere around 40 VDC and around 10 when off-hook. It should not be zero as was mine. The inverter internal to the '110 had failed in mine, whether to an external transient or other event I don't know. If yours has failed, it is time to check your warranty status (one year) and open a ticket with Obihai. Mine is being replaced - Obihai responded quickly!
VBAT value is 0 V (12.1 V)