Why aren't my updates installing?

[lakebay]

Bought a 640, used my account, signed up for Insider and installed W10.
Now I wanted to give this to my mom for Christmas so I did a hard reset. It didn't go back to 8.1, stayed on 10. Now using her Hotmail account on the phone with no Insider and it's trying to install an update for 10 but always failing

What do I do here?
Just wait for the 640 to get "official W10" and catch up?
Sign up for Insider again?

 

[charlatan1978]

Now I wanted to give this to my mom for Christmas so I did a hard reset. It didn't go back to 8.1, stayed on 10.

That is correct, to get back to 8.1 you would need to roll back using the Windows Device Recovery Tool.