Unfortunately reflashing it didn't resolve the issue.
I'm afraid I'm going to have to completely disassemble this and troubleshoot. I will probably redo steps multiple times, miss obvious things and generally waste a lot of time. But this is the way things go...
And if I get a working N900 out of it, then I'm all in!
@groovestomp it's never too complicated with a heat gun!
Oooh, the teardown does not look too complicated.
https://www.ifixit.com/Teardown/Nokia+N900+Teardown/24861