Read here https://forums.macrumors.com/thread...-bootrom-upgrade-instructions-thread.2142418/ it's a two step upgrade.I have a 2009 4,1 that I upgraded to 5,1 via the usual firmware flash. I normally run Ubuntu on it, but I have a High Sierra disk that I can drop in for firmware updates.
I finally bought a Mojave compatible PC GPU (Nvidia GT 630 2 GB) so I could get on the NVMe train to perfomance!
I booted to HS and downloaded and ran the Mojave updater. It correctly says that I need to shutdown, hold the button until I see the lights flash or a long beep.
When I folllow these instructions, I wait and after a while (15-20s?) the power lights flash quickly, then more slowly, then stop and the CD-ROM opens. The beep never happens. But I've tried releasing as soon as the fast lights flash, or after.
In either case, the system sits with no video and no other apparent activity. I can wait 30-60 minutes and nothing happens. If I power it off and back on at this point, it boots twice and then I am back in the old OS and it still wants me to update the firmware.
Any ideas what might be happening? Thanks in advance.
Last edited by a moderator: