Just deleted my navcore or one of the files on One XL 30 series w/boot 5.5136 and navcore 8.083. I held down on/off button to restart it , but didn't work. I tried a few times , and still the same - went to splash screen and stopped. So connected to usb on the front of computer. Restarted , still nothing. Connected to rear panel of the computer where all the rest of the usb's are. Then restarted and VIOLA !! Came back to life and was connected.
Hope this will help others who do this ( by mistake of course )..

I am also installing map Eastern_US_and_Canada_975_7690 with navcore 8.083 the original