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#11
You would have to do a "change product code" and switch to 10 Home to do the slmgr /ato and activate 10 Home. I've had similar activation issues happen when doing the "change product code". The other option is to go to the activation screen in settings and then clicking on the "activation troubleshooter". That's worked for me at least once. That option is only there if activation fails though.
Settings > Update & security > Activation.