New
#11
Since it seems like slmgr /dlv will not run properly on the computer, something appears to be really wrong with the Windows installed on it. The fact that you are only on build 10586.164 also points to that - you should be on build 10586.494 if you don't have the Anniversary update.
You can try running:
slui 4
in a command prompt (admin). That might bring up the phone activation screen and you can try phone activation.
Unfortunately, though, it seems like the reality of the situation is that you really need a clean install to wipe everything out and start fresh. As of yesterday the Anniversary update build of Windows 10 was still activating from manually entered Windows 7 product keys but we're not sure how long that will last. Pretty much forget about the OEM:SLP Windows 7 product key that showkey is showing - that is for use only when restoring the computer from factory provided software. You want to use the product key from the COA sticker.