Bios is displayed with the Dell Update app.   In the meantime, yesterday with the help of Dell, discovered that both fans are failing.  Technician will be out in the next 3 days to replace the fans.  thanks to all for your help.  
Current bios is 2.8.1 - Tried to install bios 2.9.0.  Says install successful, but the bios is still at 2.8.1.  Trying to resolve the error 511 - fan not responding.
XPS 8940, error 511, tried to upgrade to bios 2.9.0