Mac Forum / General / Hardware / May 2008

You probably had a momentary disconnection of the power cord, or
something like that.

I suppose you didn't notice the line in the instructions which says
"Note: Avoid moving your G4 Cube while it is flashing software."

That was bad luck.

Have you tried repeating the mechanism for starting the firmware
installation?

Judging from the web site it requires holding the programmer's button in
while pressing the power button.

http://docs.info.apple.com/article.html?artnum=75129

Repeat everything starting at step 4 (putting the Cube on its side).

I expect that this procedure will work. Apple should have designed the
firmware in a way where it has an unchanging "front end" which gets the
computer running sufficiently to recognise the firwmare update request
and then updates the main bulk of the firmware (which is loaded from
disk). The mechanism should be designed to be as reliable as possible,
able to recover from everything short of a major hardware failure.

Unfortunately, your attempts to fix the problem might have rendered the
computer unusable. In particular, removing the battery could have wiped
the information needed by the firmware to locate the firmware update
file on disk. If Apple was sufficiently paranoid then they would store
this information on the disk as well, and the firmware update procedure
would look for it there, protecting it against a dead PRAM battery.

If restarting the firmware update doesn't work, then the computer is
probably dead. Partially updated firmware will not be able to start the
computer in any meaningful manner, as the code that starts up the
computer is incomplete.

The only way to get a computer back into a useful state from this
condition would be whatever method the manufacturer used to get the
firmware onto the system in the first place. This is likely to require
removing the main logic board and connecting diagnostic equipment
directly to it, which can only be done in a factory or possibly by an
Apple service centre if they have the right equipment.