Incidentally, a day after I asked the above question, my N900 is now dead as dead can be.

I'm guessing eMMC/rootFS corruption as the N900 simply gets stuck in the loading screen after the Nokia logo at boot, although I COULD flash the rootFS.

So, this related to rootFS / eMMC data write corruption due to undervolting? Because I can say that this is the first time I've seen an N900 die DUE TO USE rather than being dropped or anything.