I remember the flashing jigs i have seen back when i was a part of allaboutsymbian's staff and nokia used to like me but i have asked few people i know and like you said the jigs they have here use the USB.

BTW, with the assitance of a very helpful member of TMO i acquired a fresh backupmenu images and restored them to my N900, everything works except the USB

Also tried flashing without the battery. All i get is a contant orange/yellow glow from the led when i plug in the microUSB, no other signs of life.

I guess a trip to the official Nokia service center is inevitable, thanks a lot guys, you have been most helpful!