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Power down you machine and remove everything from your controller except power, machine communication, and the monitor.
Power back up.
Does the controller boot farther into PathPilot?
If yes, attach one USB at a time until you find the problematic USB connection.
If no, power down controller and restart (to get into bios, see below)
To get into BIOS, restart computer and rapidly press Del (for brix, rev c, rev d etc.) or F2 or F10 (tower controllers), If your date and time are accurate, and you still are having issues, restore to factory settings.
View file name PP v2 restore from drive.pdf