EXFO FTB-500 (Window XP) - Manual (Page 282)

Troubleshooting
272 FTB-500
Restoring Your Unit to Normal Operation
Restoring Your Unit to Normal Operation
Your FTB-500 is set to start using the standard Windows startup sequence.
However, you can also use the emergency system tools feature if you need
to:

check the disk integrity

back up some files directly onto a USB storage device for recovery
purposes

revert your unit to its initial state (as it was when you purchased it) or
restore it with a specific Windows image (WIM) that could have been
provided to you by EXFO customer service, for example.
C
AUTION

Before starting the recovery operation, connect your unit to a
power outlet using the provided AC adapter/charger.

DO NOT TURN OFF your unit while the recovery operation is
underway. Doing so may severely damage your unit. Damaged
units will need to be sent back to EXFO for repair.