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Camera-specific Development / Re: Canon 5D Mark III / 5D3 / Firmware 1.2.3
« on: May 08, 2020, 05:46:51 PM »HELP
hey all
hope someone can help
i have a 5d mark 3 with 1.3.6 firmware.
Is there any way i can downgrade the firmware to 1.2.3
Yes, this is from the ML 5D MKIII nightly Build page and it works:
Downgrading from 1.3.6 is possible, but tricky.
Whatever you do, do not remove the battery in the middle of a firmware update!
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One single card required, either SD or CF, source, discussion):
copy firmware 1.3.6 (5D300136.FIR) to the card
launch Update Firmware from Canon menu, click OK
open the battery door ASAP, but don't remove the battery!
if you did it right, the camera will turn off (wait for a few seconds to make sure it's really off)
if you see the Firmware Update Program Loading screen, it means you have opened the battery door a bit too late; wait until the camera turns off and try again!
open the card door and remove the card from the camera (do not close the battery door; also leave the power switch on; the camera should stay off)
copy firmware 1.2.3 (5D300123.FIR) to the card
put the card back into the camera, close the card door
you may leave the original 1.3.6 FIR on the card, or you may delete it; doesn't matter
close the battery door; you should see the Firmware Update Program Loading screen
if you get an error message at this step, remove the battery and reboot
confirm the firmware downgrade from 1.3.6 to 1.2.3
a successful downgrade should take about 4 minutes.
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I have done this so I know it works.
This is the most important step: open the battery door ASAP, but don't remove the battery! - ASAP means immediately. ANY delay and this will not work. But it does not do damage, just means you have to try again but faster!