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Help, PowerBook G3 Pismo not booting after firmware downgrade attempt!

rvarbean

rvarbean

macrumors newbie
Original poster
Sep 30, 2019
4
1
Space
Hi all,

I tried to downgrade the firmware on my Pismo from 4.1.8 to 2.7 to try to bypass Apple’s ram compatibility check in the latest firmware by modifying the open firmware script within the 2.7 updater in Mac OS 9, and it seems to have flashed ok, (progress bar filled, and machine rebooted), however it did not boot at all as soon as the update was completed. Caps lock key lights up, but no chime or video. Can’t reset PRAM or anything either. AFAIK I have bricked the bootrom, if this is in fact the case, is there anyway to reflash the chip, preferably without unsoldering since I don’t have any skills with that sort of thing. Please let me know if there’s anything I can do since I paid $400 CAD for this machine! 😔

Thanks a ton.

-Ben

 
I don’t have an answer regarding the bootrom, but occasionally my pismo won’t boot at all until I disconnect the PRAM battery from the logic board - pop the keyboard up and unplug the small connector bottom right with the red/white wires. Then you can plug it back in again once it boots up.

Could be worth a try.
 
AphoticD said:
I don’t have an answer regarding the bootrom, but occasionally my pismo won’t boot at all until I disconnect the PRAM battery from the logic board - pop the keyboard up and unplug the small connector bottom right with the red/white wires. Then you can plug it back in again once it boots up.

Could be worth a try.
Click to expand...
I tried that already, no luck unfortunately.
 
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