I had the same problem. Nothing worked and it turned out to be a corrupt bootloader. (Therefore however many times I tried it was never going to work)
The non-Nokia repair person (out of warranty) fixed the bootloader and I re-flashed with all the correct firmware and it is running again for $80.
I did have a recent backup, but did lose everything in the mydocs folder. Luckily there was nothing important in there.

markn,

thanks for the response

i think my n900 is under warranty from nokia

how can i contact them

Depending on where you live - look for a Nokia Care centre here
Thanks
http://europe.nokia.com/support/repa...ir/care-points

I'm reading of many who had similar problems. This is a serious flaw.

You've been told already good sir, it's not a flaw. It's a single point of failure. The silent majority do not have the problem you do.