To summarize the other 200+ message thread on this issue:

There seems to be an odd problem with the documentation package that is part of this update. If you have removed all of your User Guides from the Documents folder on the built in memory, the scripts that run when the package is installed fails halting the installation half way and leaving your tablet desktop in an unstable state.

The way to recover is to just fall back to the old firmware flashing method, do the two pending SSUs (unless there is already an updated firmware out ... there wasn't when I ran into this issue) and then restore from backup using the backup utility (you did do a backup when prompted to before the SSU, didn't you?).

There are several causes to failure.
See this post: http://www.internettablettalk.com/fo...&postcount=304
My advice:
Before applying a SSU make a flashable full backup of the system (see http://www.internettablettalk.com/fo...8&postcount=31) and save it on your PC.
Better advice:
Run the system from mmc, you can make a full backup trivially with tar, and restore it by simply unpacking the tar.gz file. You do not need to install bootmenu to boot from mmc, just configure the tablet with "flasher-3 --set-root-device mmc"

maacruz could you provide real links to the posts?

My problem with N800 is different but looking similar. After feature update bootmenu has disappeared as usual. After reinstalling bootmenu my NIT boots from internal flash only. When I try to boot from mmc it passes bootsplash till gauge is full 100% and hangs.

Opps, I'm sorry. I did cut and paste the url and it seems it wasn't the post url.
Fixed now.

This update really screwed my N800. I had the same problem with the reoccuring loop where the status bar reached about 80% and then it restarted again. I tried doing the manual flashing but was not able to do so. The install wizard was able to download the software but not update my device. It said to check the USB cable. I have done the same process in the past many times using the same one with no problem. I tried the process again and the USB logo on the top right corner was not showing up as it should when flashing. I tried time and time again with no luck. Right now the device won't even turn on. I charged the battery again last night and it still didn't turn on this morning. I don't know what else to do.

Any comments/suggestions from anyone?

Thank you.