I have been asked to relay to the best of my ability how to get back to 2.0.1 OEM if you are also having problems using the methods provided in OP.
I will do my best...but it was very much my experimenting around. I was praying the whole time I did not do something unrepairable.
First and most important is that I can only say that this works for sure from 2.0.1 w su.
The reason is that before I upgraded to 2.1 I did an advanced nandroid backup of 2.0.1 w/su. None of my attempts to restore from 2.1 worked. I always ended up with a blank version of 2.1...ALTHOUGH...now that I think about it considering how I ended up reseting... it could work from anywhere I guess.
So first I restored to 2.0.1su (may or may not be necessary)
I downloaded DroidBR (placed both on sd card as suggested)
I mounted Droid to PC and opened adbshell
typed SU
then flashed recovery image (
flash_image recovery /sdcard/recovery.img)
I was unable to flash the boot.img...said I did not have permission...which is wierd no?
I rebooted into recovery anyway and got the OEM recvoery menu. So I figured I was close.
I tried to install the original 2.0.1 updat.zip we all used to update manually back in Nov...but got some error. So I tried a factory reset. This worked...I saw the unpacking image and then had phone reboot to the original set up menu (had to contact verizon and press 1 to program phone). Skip set up!
This put me back to 2.0.1 OEM but still had su and busybox. From here I mounted the phone again used the ADB Shell Commands I found in this post to remove su and busybox...
[How-To] Back to Stock, no su, no BusyBox, etc. - Droid Forum - Verizon Droid & the Motorola Droid Forum
(if using adb shell, don't forget to put phone in USB debugging mode)
su
mount -o remount,rw -t yaffs2 /dev/block/mtdblock4 /system
rm /system/bin/busybox
rm /system/xbin/busybox
rm /system/app/Superuser.apk
mv /system/recovery-from-boot.old /system/recovery-from-boot.p
after than I did one more factory reset...and VOILA!
Disclaimer....I am nothing near a programmer or developer. And I cannot guarantee that there are not still issues that I have not resolved from this. I cannot be held responsible if this does not work or worse.