Are you sure you installed Pro and not Home by mistake? Yes, of course it'll fail to activate since it's only a generic key. But why would MTK activate it as Pro? Can you try with KMSpico or KMS_VL_ALL?
Yep just checked and it says Windows 10 Pro I've just clicked on Activate Windows under System and it throws up an error message of:- We Can't activate Windows on this device at the moment. You can try activating again later, or go to the Store to buy genuine Windows. Error code: 0x87E105DC
Yes, MSDN and Win10ISO page have same ISOs. But why should he use Accessibility tool if his Pro was already activated? Surely there must be an easier way... Didn't know this. Too bad. So it means he has to use only the Ent. ISO to install. What are you talking about? Open MKUBA50 14393.0 Direct DownloadLinks [ISO] on first page and check again.
I like it since I don't use the store much, but they're starting to put some AAA games on it, so I'll stick with Pro for a while. Besides, I already know how to turn off the telemetry and such, anyhow.
I've read several posters who had the pro turned into enterprise (and ent into pro) after using MTK activation. Maybe they still were on 10586?
Post - Read a few posts before and after that one. Done it many times - no prob at all. Enter Enterprise gVLK and run abbodis' KMS VL All (my sig) - job's a good un.
By any chance, does anyone have en_windows_10_enterprise_version_1607_updated_jul_2016_x64_dvd_9054264.iso?