No I got new hero and created a nandroid backup and wanted to know if its possible to restore my old hero from the new backup ???
Go for it. Then re-try the RUU maybe. If worse comes to worse just wipe everything off your OLD phone so it's unbootable before you send it back. This won't hurt the hardware in any way.
From the adb shell on your PC
Code:
rm -r /system/*.*
rm -r /data/*.*
cat /dev/zero > /dev/mtd/mtd2
then reboot. It wont actually boot, but all traces of the system are gone. All that's left then is the bootloader