Recently I was cleaning up some malware from Asus Windows 10 laptop. It took using AV software boot disk to remove malicious software and after that I upgraded Windows 10 to the latest feature update/build (2004). Windows Update was working pulling some more update but finally stuck with 0x80240023 (WE_E_EULAS_DECLINED) error and it took a bit too long for me to solve this problem, so taking a note of resolution here.
As machine has been infected I was suspecting that I might not had cleaned up it completely but in the end it was a problem of rare combination of Windows 10 2004 with Office 2007. There was basically one specific update for Office 2007 which was failing to be installed without being able to properly say so (it was Microsoft Office File Validation Add-in update). I went for using “Show or hide updates” troubleshooter package which allows you to hide/prevent specific update from installing. Once I launched it I saw this one pending update and hide it which cleared up the error. It seems that as an alternative solution you may try to install it manually locating OFV.cab in C:\Windows\SoftwareDistribution\Download, extracting it and running OFV.msi. As I understand there is some unexpected request for user input on installation of this thing, but I end up just hiding this update, although not without trying bunch of other solution like rebuilding Software Distribution directory and so on.
Another issue with this laptop was random waking up from sleep state, which user saw as random power on, that was resolved through disabling wake up timers on all Windows power plans as well as ensuring machine being shut down instead of put to sleep (hiding Sleep option from power off menu etc.).