Did that camera actually shut down during the firmware update ?
If it did, that is pretty much a worst case scenario that is often highlighted by manufacturers as irrecoverable without a return to the service agent. The reason is that, unlike a controlled firmware installation failure, where the firmware updates can reverse the update if it detects a problem, a power failure during the writing to flash memory basically creates a totally corrupted firmware build with no 'back out' path.
In cases such as this, on embedded computers, if the boot loader remains intact, some clever IT bods install a new firmware image. Sadly I do not think such is so straight forward with the Exx series though. You need to be able to access the operating system and to access that you either need to change the USB mode for FTP communications, or directly access the OS via an RS232 engineering port within the camera. You cannot take someone else's camera firmware and clone it onto your camera as each firmware build is effectively camera specific with file CRC's and unique factory calibration data.
I am sorry to say, I think this will require return to FLIR for a new firmware installation using their production utilities.
Fraser