Q1: Unplug the camera from the wall socket for 30 seconds then plug it back in.
Q2: If you’re using iOS, you double click the home button to bring up the app switcher. Find the Wyze app’s card and flick it off the top of the screen. On Android, one of the buttons on the bottom (circle, square?) brings up the app switcher. Wait a beat, then tap the X that appears. (I’m not an Android user, thus the vague answer.)
If none of that works, follow the steps in the troubleshooting guide here: