I also followed those instructions to the letter with HTC One , Android 4.4.2. It still wouldn't connect to my home Wi-fi.
It can still scan and find all the wifi networks nearby, but only shows a Wifi notification symbol in the notifications bar at the top of the screen for networks that ar NOT SECURE.
I ask it to forget my network, but it stays in the list of scanned networks.
When I ask it to reconnect, it asks for the secure key, and pretends to connect, but doesn't. It just reverts to saying "Saved, Secured with WPA2"
The most infuriating part is that I phoned HTC ONE support and spoke for over 30 minutes to a support person in the Phillipines.
Despite al the fancy tricks with combinations of Power and volume buttons that she got me to try, there was still no solution. Not a good look for HTC !
She offered a factory reset as a last resort - I declined.
Not being able to use my WiFi is consuming my mobile data, and I'm getting really annoyed about the problem.