Hello, Technidiva.
The general info on how Office was installed and/or its general status is stored in the key :
[HKEY_LOCAL_MACHINE\Software\Microsoft\Windows\CurrentVersion\ continue next line
Uninstall\{00000409-78E1-11D2-B60F-006097C998E7}]
Under which, you may see entries like RegOwner, RegCompany, DisplayVersion, InstallDate etc. See if you can find your failed update operation reflected into. But even there are some info pertaining to that, you may not have a straightforward way to rectify the situation by editing entries. Better look at mskb and msdn library see if you get instruction there.
regards - tsuji