Yea in order to go back to 2.1 OTA you need to have stock recovery so it would be easier to just go to stock 1.5 besides the Hboot and then have the OTA update it for you.
That's a single command given to the Amon_RA recovery boot via adb:
adb shell flash_image recovery /sdcard/recovery.img
Obviously, care needs to be taken that the "recovery.img" file on the SD card is the correct one, both in version and in checksum. ( adb shell (then) mount /sdcard ; md5sum /sdcard/recovery.img ; umount /sdcard ; exit )
Pretty easy to do the whole return-to-1.5-stock-followed-by-OTA-2.1, if you have ROOT; as a matter of fact you can do everything needed from an adb shell
to the Amon_RA recovery console.
Just unzip the MR2 PB00IMG.ZIP (md5sum 9e9ad31f01bbcb05157443287f4f38dd), in there, the files needed are
4bc51796c9353efcaeb688bfb2cf54da boot.img
71a4b633bdb32de9dcdd8953fef43cdc recovery.img
d3d36f3b9a12d791a79a8135ced07c8f system.img
e0f6d36dfe808e00e3a5794158ec1a8c userdata.img
For a tutorial, have a look at the action in nandroid-mobile.sh, put the above files on the SD card, boot in to Amon_RA and then
[Attention noobs: if you are not familiar with Unix, you should not be using this. You have been warned.]
Code:
prompt-whatever> adb shell
/ # mount /sdcard
/ # for FIL in boot.img recovery.img system.img userdata.img ; do md5sum /sdcard/$FIL ; done
/ # echo I have checked the MD5 signatures and I know what I am doing
I have checked the MD5 signatures and I know what I am doing
/ # mount /system
/ # cd /system
/system # rm -rf * >> /dev/null 2>&1
/system # unyaffs /scard/system.img
end of image
/system # cd /
/ # umount /system
/ # mount /data
/ # cd /data
/data # rm -rf * >> /dev/null 2>&1
/data # unyaffs /sdcard/userdata.img
end of image
/data # cd /
/ # umount /data
/ # flash_image boot /sdcard/boot.img
/ # flash_image recovery /sdcard/recovery.img
/ # exit
... and reboot. The "Update is available" (OTA-2.1 notice) will appear on your phone before you have made it through the setup screens. That gives you a completely stock OTA-2.1 phone (plus a little trash associated with setup in 1.5, which could be easily wiped with a 2.1 FR); at that point, if you wanted, you could make a Nandroid backup of a completely stock OTA-2.1 phone.
Here's a cool trick that other Android phone users know about, but Eris rooters never seem to use: the 1.49 S-OFF bootloader allows you to boot the Amon_RA recovery
without ever installing it.. How do you do that, you say?
Put the phone into fastboot mode and shove the thing across the USB for immediate booting:
fastboot boot recovery-RA-eris-v1.6.2.img
No need to flash over the 1.49 S-OFF bootloader for the OTA update, as you point out - it would be dangerous to do so anyway, because the OTA install re-flashes the recovery partition back to an HTC version for 2.1. I don't think the radio version matters either - it also gets flashed by the 2.1-OTA anyway. Neither the OTA nor the OS care about what they are during the 1.5 boot. (The 1.17.605.1 "stock" recovery must be in place before the OTA-2.1 runs, because the Amon_RA recovery boot does not process the OTA-2.1 update-script correctly.)
eu1