RaTTuS wrote:and it's now working again
Well, the files haven't changed in the last couple of days, so it must be something wasn't written properly in the update procedure.
You can see when things change:
I have just tried an rpi-update (on raspian) and it worked fine.
So, when it fails make a note of what distribution you are running. How old the previous firmware was, and ideally take a copy of file in boot partition when it doesn't boot and again when you get it working and do a diff of the files.
Possibly a file is not getting written by the script, or it is getting corrupted.