It’s a very large update that effectively replaces the O/S. Tablets and micro-PCs... especially those with very limited memory resources... will have difficulty getting this done. If you have any means of adding an external memory card or something (16GB or higher, perhaps), then that would certainly help as the update shuffles files around.
Too late to add memory once the update has started? Maybe he can turn off the power, risking a the integrity of the OS and run to the computer parts store. Else, just wait.
Whatever it was he wanted to do when he turned the computer on can just wait. :-(
Well that probably explains it. I’ve got lots of videos on my drive.