Your thermostat

[MMSH1]

Yesterday began getting a "your thermostat needs to shut down to recharge its battery" message.  Charged unit by USB for over an hour.  Replaced display to its base.   This yielded a "thermostat is shutting down message" and all has gone dark/dead.   I cannot get to the NEST display settings at this point because keeps it shutting down.  NEST was installed by HVAC company in 2018 with current AC unit (6 yrs ago).   Only other issue was battery related after power went out; a USB recharge of the display appeared to resolve it.   Does the battery need to be replaced?  What needs to be done next?  Any help is welcome

[CoolingWizard]

@MMSH1 

try placing to display on a USB charger for a minimum of four hours. Then reattach your display and go to settings then equipment and then power 

You need to see LIN and battery voltagevalue and report it back to me. 

AC Cooling Wizard