So, your n900 is properly flashed with combined and emmc firmware right?
R+D mode is disabled too, right, well then you should have a working phone mate...
Did you try to take out the battery for at least some minutes (and holding the power button for a while when battery is out?)... The phone sometimes really acts weird and memorizes a lot of stuff even when the battery was out for some seconds.

Try it...

:cheers:

..::J4ZZ::..