I have a Motorola Backflip running the latest AT&T firmware, and I'd like to downgrade it back to Android 1.5.
Now, I learned early on the Radio/Bootloader cannot be downgraded. After some digging I've found a thread on ModMyMobile that instructs you on loading the Radio image from the newer firmware into an SBF containing the older Android version. This can then be flashed from RSD Lite, and it'll keep the new radio and bootloader while loading the system partition of old.
However, an update released after that was post was made put the kibosh on that approach. It now refuses anything that isn't an official, signed SBF.
Here's three ideas I think might work, and I'd like your feedback on them:
1.) I have the MBN files extracted from the Android 1.5 SBF sitting on my hard drive. Is it possible to extract the contents of the systemsec.mbn file, load it into a flash-able ZIP; and then flash it via the custom recovery I have on the phone?
2.) If someone out there were to provide me with a backup of the old firmware, created with jr00ds recovery, could it then be modified to remove everything but the system partition, and then simply restore the modified backup to my device?
3.) This is one I know will do the trick: if someone on these forums has an old, battered Backflip that still has Android 1.5 sitting on its ROM, I could just transplant the motherboard to my pristine unit. If any of you have one you're willing to sell cheaply, please let me know!
Before anyone asks the obvious "Why so much effort for an outdated device/version of Android?", it's purely for nostalgia. This was my first Android device, and part of me would like to relive it. Because, frankly, the 2.1 update was just plain terrible.