It appears that the blanking issue may have become permanent. Even leaving the battery out for 10 seconds did nothing.

a log of the latest events. Sadly i was not running the debug version when it all started. Hope there is something in there.

Try restarting mce ("/etc/init.d/mce restart")

tht resulted in the screen dimming but not blanking. But fiddling the display settings a bit seems to have shaken that into working order. Wonder what is making mce go nuts.

I ran into a problem that may be the same as tso's. It started after I installed Diablo Turbo, but I can't say for sure that was the cause. Unfortunately, I ran into it while traveling and so I couldn't get into the N800 with SSH.

The symptoms were:
1) No blanking (When attempting blank from ASUI, get "An application has paused..." even when no applications started)
2) Unable to unlock -- short-press Power unrecognized
3) Unable to power down after locked -- long-press Power unrecognized
4) Unable to use Home key for (default) task-switcher
5) Unexpected changes to the "auto lock" (I prefer it off) and "stays lit" (I prefer "when charging") settings

I had to pop the battery a number of times in debugging this. I think, possibly, the cause was related to either powering up or powering down while the device is on charger; and, possibly, was finally able to overcome it by booting and then shutting down via ASUI.

mce acted weird on me some time ago for apparently no reason, may be it has a race condition
Please, try this kernel and see if it makes the problem go away for you:
https://garage.maemo.org/frs/download.php/9552/zImage

Well i am not really up to speed on doing kernel installs outside of deb...

Just a quick refresh:
From your (linux) PC: flasher-3.0 -R -f -k zImage
or from your tablet: fiasco-flasher -R -f -k zImage

thanks, will give it a spin

well it booted. But screen blanking is still misbehaving.