According to support suggestions, I followed the procedure listed specific to my case (BIOS 1.10.2), and this solved the problem. Precision 7540 and 7740 Stops Responding When Updating BIOS from 1.10.2 to a Newer Version    
I initiated an update procedure via Support Assist for several important and recommended updates, which included a system bios update. The system bios update is now stuck at 100% flash progress for more than 20 minutes now. Not sure what to do, turn off or what?  
Precision 7540 system bios update - flash progress stuck at 100%