Nokia software updater will naturally fail. There is no more Nokia corp. support ...hasn't been for yrs for the n800/n810....we the community members maintain the stuff here.

At that point it fails... it will work offline and ask you to provide the file in question...your firmware. you use the browse button...to select the firmware you have in your computer. IF you have the necessary firmware ...that is. Just running the software updater will not help...you need the proper files as well. the updater essentially takes the firmware file and completely reinstalls the operating system on your device. In short ...that is what the software updater does.
Considering you are posting essentially the same dilemma in 2 subforums ...please keep your questions in one or the other...not both...it makes it harder to help if you play tag through the forums asking for help along the way.