Hm, this is interesting. I probably should get myself a spare N900 so I can do some devel work... I don't have the time to finish a "code -> debug -> get working" cycle in one day anymore(and actually use my N900 on a daily basis), so I'm going to need to get myself a second device. Shouldn't be too long now that I've got a good job... Might be able to order it next week...

If you guys take a look at the code, the word 'chrooting' is being displayed from the rootfs-based pre-BM system, and anything after it is being displayed from the chroot. I'd look at the beginning of BackupMenu.item and see what isn't available so it won't start...
And yes, if Q works, then that means BM is actually booting, it just isn't displaying. text2screen problems perhaps?