You can check the turn function of the Digital Crown by simply pressing to display the apps grid (or list) then turn the crown, it should scroll or zoom. I suggest a forced reset (reboot) to eliminate software glitches as the first step of self-help, simply press and hold both the Digital Crown and the Side Button (together, at least 10 seconds) until the Apple logo appears, then release the buttons and let the watch reboot. Then check again.
Note that the unlock operation for Water Lock seems to need a fairly enthusiastic turn of the Digital Crown, sometimes 2-3 continuous turns. I usually just spin it between my thumb and forefinger.