I didn't make it!
Without uninstalling 2.4, the repair function will work (even if you have moved the AA folder to another location, drive). Just run the AA exe file and click the Repair function. However - CAVEAT - you must also then apply the 2.5 patch. Additionally, if you have moved the AA folder to another location, the patch will err message and not install. You MUST have AA in its original location for the patch to apply.