Hi,
Using Office to get the updates didn't work for me but I found a way to fix Windows Update, following the instructions in the pages linked by PiergiuseppeQuarato AND in this page: https://www.tomshardware.com/news/microsoft-windows-8-update-patching-modern-ui,26504.html
Summarizing, I downloaded all of the following packages and installed them in this order, turning wifi off:
- Download and install update KB-2919442: http://download.windowsupdate.com/c/msdownload/update/software/crup/2014/02/windows8.1-kb2919442-arm_506ed7113697c597c2859d295d562fa4311834ec.msu
- Download and install update KB-2932046: http://download.windowsupdate.com/c/msdownload/update/software/crup/2014/02/windows8.1-kb2932046-arm_fe6acf558880d127aef1a759a8c2539afc67b5fb.msu
- Download and install update KB-2919355: http://download.windowsupdate.com/c/msdownload/update/software/crup/2014/02/windows8.1-kb2919355-arm_a6119d3e5ddd1a233a09dd79d91067de7b826f85.msu
- Reboot when asked to do it
- Download and install update KB-2938439: http://download.windowsupdate.com/d/msdownload/update/software/crup/2014/03/windows8.1-kb2938439-arm_4a536d9ddcd9993cbe4fbc309ebd50a18d65f954.msu
- Reboot again
- Download and install update KB-2937592: http://download.windowsupdate.com/c/msdownload/update/software/crup/2014/02/windows8.1-kb2937592-arm_860c83a0cccc0519111f57a679ae9f9d071315e5.msu
- Reboot again
- Download and install update KB-3173424: http://download.windowsupdate.com/d/msdownload/update/software/crup/2016/06/windows8.1-kb3173424-arm_e11b6837c0586d2b8d887f3bc33b3372fe83c8c7.msu
- Download and install update KB-3172614: http://download.windowsupdate.com/c/msdownload/update/software/updt/2016/07/windows8.1-kb3172614-arm_3d918d6c809bf6f57c8fcefa5db5c739e1754426.msu
- Reboot again
- Turn on wifi and search for updates (it worked for me now)
I really find pitty that Microsoft gives such a poor support for their own devices, forcing us to follow random procedures to perform an update. At the very least they should have a page explaining the procedure.