Yes do not play with BIOS downgrade/upgrade, without battery it can kill the Motherboard.  This is very rare that BIOS is giving error of non complaint battery.  Remove both main battery and coin cell,  Release charge by holding power button for 30 seconds.   
I have an xps 13 I recently changed the battery because orginal one was no longer holding charge. I bought the new battery from parts-people.com initially it worked like a charm bringing back the old full charge backup of over 14 hours then recently dell pushed through the latest BIOS and all of a sudden the new battery is not recognized the orange status led continuously flashes, preboot support assist detects a non compatible battery and in BIOS under battery information the status switches between 'Idle' and    'charging' and  'disconnected' frequently computer rarely turn on with only battery but often will not even show any light. I was thinking how a BIOS update suddenly found that I am operating on a non OEM battery after all I purchased the battery from parts-people.com. I did all the trouble shooting including the powerdrain after disconnecting the battery and charger, turning on without battery and putting the battery battery back on etc I also restored BIOS to 'last known good configuration'. I am afraid to do a BIOS downgrade as they computer may just shuts down during the process. Any inputs highly welcome 
Battery not recognized