Twice now I have hit the same issue while updating F2/5-221 from Tos 5.1.45 to tos 6.0.530 (.530 as the intermediate step to latest)
The main bug (as I see it) is that the usb init-boot fails to be re-written correctly. for the (future) Tos6 installations/re-installations.
I know this since I just decided to reset to factory default my F5-221 after several system errors* started showing up (following update).
Having reset I realised I was not able to reboot my device. In case no-one else has noticed, the "old" legacy iinitboot has a typo which shows up on console monitor as:
"Booting form ...... disk"
and, in this case, that was as far as it went.
Previously I had updated F2-221 and similar issue showed up when doing something similar but I wrote that off as a fluke. (In that case a re-install reverted to Tos5.1 which it should not have done.)
In both cases I felt obliged to prepare new usb drives with the appropriate image file(s). In the case of the recent F5-221, having removed the case, replaced the usb and refitted the case the re-install went directly to Tos6.0.648.
*I have downloaded an error report and that has gone to @TMSupport.
content = """Notification email: test email generates "logout", but click on screen re-instates. Cannot set new email (custom) attributes.
Lan aggregation (active backup) does not survive reboot.
That is just 2 things found so far."""



