can't unblock device

Hi. I had to block my son's device from internet temporarily. I used the Nighthawk app on my phone to do this. Now I want to unblock him, but when I select his device, the required button in the Nighthawk app -- the button that says "internet" -- is completely unresponsive.  I have tried tapping it and dragging it a hundred times.  

Another piece of information: during the time that he was blocked, I changed the setup of the Nighthawk to "wireless access point mode," which is what I wanted all along, although the setup wizard did not offer it. So the Nighthawk is now passing IP address requests through to the main Fios router and extending my wifi coverage in the house. It works fine for everyone else in the house.

Making matters even more strange, my son's device will insist on switching over to the (non-functional, for him) Netgear 2.4 ghz network, even when the main router's network is available and has a stronger signal. 

I tried logging onto the Netgear to restore my son's access, but his device is not listed there at all -- again, totally weird, given that his device is visible on the app.

Any suggestions would be appreciated.