Extra info - I also have a Win10-upgrade-from-Win7 and it does not have a Schedule Service - what it has, is a Task Scheduler. It already has a working Office, so I have not tried to install 2013 in it.
Registry edit : I looked for HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersionAppCompatFlags but could not find it.
Older version of Office : NO Office had previously been installed in this Win10
Uninstalled failed Office 2013 : NO - no need to, because I'm trying this out on a clone of the source Win10, so new attempts are done of fresh clones of Win10 that have not been contaminated by previous attempts.
Clean Boot : yes tries that, as well as from Safe Boot, and 'as an Administrator', and from C:\
Had not renamed the helpfolder - will do that as soon as I can.
I looked in Event Viewer - which is a very complex program - as best I could and found for a time of 2013 install :
Error: Failed to install product:
C:\MSOCache\All Users\{90150000-00E1-0409-1000-0000000FF1CE}-C\OSMMUI.msi ErrorCode: 1603(0x643).
I've tried MicrosoftEasyFix50450.msi
I have NOT yet tried the following script 'as an Admin' :
@echo off
sc config winmgmt start= disabled
net stop winmgmt /y
%systemdrive%
cd %windir%\system32\wbem
if exist repository.old rmdir /s/q repository.old
rename repository repository.old
for /f %%s in ('dir /b *.dll') do regsvr32 /s %%s
wmiprvse /regserver
winmgmt /resetrepository
net start winmgmt
net start SharedAccess
net start CcmExec