Stuck with wrong firmware

[Joselita]

Hello ! I have a Mac Pro 4.1 . I flashed the firmware for installing high Sierra a while ago . Lately something happened that seems to have bring back the old basic firmaware and now computer goes only on R mode . How can I get my computer back ? Should I downgrade and how would I do that when the OS X base is high Sierra!???

 

[tsialex]

Seems you previously used a patched install to install High Sierra, no? Try installing ElCapitan, the last supported macOS release for a early-2009 Mac Pro.

After you get it working, check the installed BootROM release ( > AboutThisMac > SystemReport > Hardware > BootROM version).

 

[Joselita]

Seems you previously used a patched install to install High Sierra, no? Try installing ElCapitan, the last supported macOS release for a early-2009 Mac Pro.

After you get it working, check the installed BootROM release ( > AboutThisMac > SystemReport > Hardware > BootROM version).

Yes , it was a patch of I remember well . I will look at the link you shared , I tried many times to install El Capitan but I was not successful as being in recover mode doesn’t give me too much latitude , and,,,, I am a former geek lol don’t follow the train for many years ... thanks for you presence and sharing !! ??

 

[Joselita]

After trying again , same error message trying to install Yosemite on a HDD external. Here is the setup and the error message . I can’t figure out what I am doing wrong ?

 

[tsialex]

Yosemite don't understand disks that were previously formatted with APFS, you have to nuke and reformat. Also, did you backdate the clock before October 2018 (when the signing certificates expired)?

 

[Joselita]

Yosemite don't understand disks that were previously formatted with APFS, you have to nuke and reformat. Also, did you backdate the clock before October 2018 (when the signing

 

[Joselita]

Thanks for the path !