Is there an explanation of the fremantle startup process - in particular how the desktop gets launched.

What happens just after the graphical animation
and also when the 5 dots are flashing after time/date entry has been made?
Are there log files created by that process?
Is it possible to get a VT open to observe what's going on?
Can I easily boot to a SHELL and try starting that part of the boot process manually?

I have an n900 which doesn't boot, though I can r/W to the filesystem from nitdroid. Whilst I could reflash I'm intrigued to figure out how I'd debug this & what tools/techniques may apply