MAX3 won't connect to Wifi anymore

I got a MAX3 one week ago. Everythink worked fine until this morning. Then, suddenly, it wouldn’t connect to Wifi anymore. It just asks the password, but when I tap on “connect” nothing happens. Just five minutes before, it had been logged into the same network. Reboot doesn’t help, I do not find any detailed information about network status either.
What can I do?
Thank you,

Have you tried to make the reader forget the access point name? You should be able to do that by long-pressing the name. You’ll then be asked to re-enter credentials when you try connecting again.

I finally found the factory reset. As I hadn’t done much with the device, I just deleted everything. Now it works and I have been able to install the new update. I hope, the problem will not appear again. Forgetting the acces point name didn’t work before the update.