Clean and simple AKU 3.5 for the Sprint Apache

[Merlin1716]

I've got an original PPC 6700. It works, if that's what you call it, but it will turn itself on and off sporadically, self-activates flight mode, refuses to turn off the backlight, then won't turn it on - - you know, standard sprint issue
So - - I might be ready to try installing what seems to be (according to the reviews above) a pretty nice update. However - - a bird in the hand is worth two in the bush. Although I'm not really happy with the sprint version - it does work (more or less).
What I need is a method to back up what is currently flashed into ROM on my PPC 6700 so that I have the original firmware AND a method to restore that backup if the new stuff somehow becomes unworkable. I can hear sprint laughing now if I were to flash the PPC, and have second thoughts later on.
Please let me know how to download my current ROM for safe keeping, with instructions on how to restore that file later, should the unthinkable happen. I would assume that the restore would involve invoking the boot-loader mode and copying the files back to the ROM - - but a step-by-step would be appreciated.
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Thanks to all who have worked so hard to improve a pretty sweet little piece of hardware that sprint seems to have abandoned.
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Merlin