u can force it into boot loader and then use MSU to update. thats what i did when i had similar issues.
MSU - motorola update software from their site
u need to first reach recovery menu by taking out battery hold power and camera, until the M in the circle appears then hold cam and vol up.
u should get the !!!<traingle> just messing with volup and cam until u get the options. also just thinking if you have reached this method, you could also go the root of using the nandroid update.zip which will allow you to flash up various versions on the milestone.
hope this works for you.
if not you could always use ur insurance and tell them it just died lol (wipe mem card first)
HTC DESIRE GSM (VODAFONE UK) S-LCD
unlocked by default
VillainRom, or AOSP
ASUS Transformer TF101 UK