This error will occur if you upgrade to the new ScreenOS image and still have the OLD signing key on your device. The boot screen on the console port will show this message:
********Invalid image!!!
********Bogus image – not authenticated!!!
Fips check failed
Done
To recover from this error and allow the device to boot you need to delete the signing key.
delete crypto auth-key
Then reboot the device and the new ScreenOS should load. Then follow the instructions in the kb posted by Vikas to install the updated image key.