I am having the same issue. I am a Nokia Representatives and usually get preproduction units. My N900 Kept rebooting and now it would not turn on Anymore. Just Nokia Logo comes on without backlight, but then it restarts again.

I tried to flash it, but it kept giving me error "To flash the bootloader, you have to supply the X-Loader image." I tried latest image, but it would not work. I tried it in Production mode and R&D mode.

The Top line says: "SW version in image: RX-51_2009_SE_3.2010.02-8_PR_MRO"

And the bottom line says: "Version of 'sw-realease' : RX-51_2009SE_1.2009.40-2_PR_MRO"

See the image

Please help, how can I get this thing to turn on?

Ravi.