Bit locker recovery key

Our Dell inspiron 16 5640 laptop was just returned to us from warranty for no power up. The bit locker key was typed in and accepted, (assuming it was accepted) twice. However the screen goes to black and then states keep your device on and we'll look for solutions again in 30 minutes counting down??? Why is it not booting back to normal at this point. Not tech savvy.  Anyone else have this problem after a warranty repair?