Well, it DOES work.
I had a brick today, was going from 140.0.0.0.0 to 141.0.0.0.0, & TBH it has been a while since I have done a firmware on my 5,1's.
With no progress bar I was distracted & let go off the on sw too early........f**k!
To my distress, yes, totally bricked. Some time ago I purchased a MATT Card, Just in case, you know, to be sure, to be sure.
Looking where to plug the card came across this thread.
Downloaded the firmware restore tool:
https://support.apple.com/kb/DL1320?viewlocale=en_US&locale=en_US
Burnt to CD, & followed the instructions:
- Make sure that the computer you are trying to restore is plugged into an AC outlet.
- Turn on the computer and continue holding the Power button. The sleep LED will blink rapidly, then slowly, then rapidly (3 quick blinks, 3 slow blinks, 3 quick blinks).
On Macs that use a tray-load optical drive, the tray will open to allow the Restoration CD to be inserted.
Insert the Firmware Restoration CD while the lights are blinking or tones sounding, then release the Power button. A long tone is played once the recovery process has started.
- A progress bar appears beneath an Apple logo on a gray screen. The progress bar indicates the firmware is being updated. Do not disconnect power, shut down, or restart the computer during the update or you will need to start the restoration process again beginning with step 6.
It worked as advertised, complete with progress bar.
BTW, I had the progress bar until I had done 140.0.0.0.0
Of course wouldn't boot Mojave, so I found an old Mountain Lion disk which booted OK
Now I was at firmware MP51.007F.B03.
Found my old 10.13.6 install & proceeded as per thread by you (tsialex), thanks again!
https://forums.macrumors.com/threads/mp5-1-what-you-have-to-do-to-upgrade-to-mojave.2142418/
Now all good with firmware 141.0.0.0.0
Many thanks to you guys, couldn't have saved the day without all this info.