Please follow these three methods to troubleshoot;
a.The collar may have run out of battery, please use the included charging cable to charge it for 2 hours.
b.The collar has entered protection mode, if the dog barks more than 6 times, the collar function auto-locks for 30 seconds and the screen flashs"P", please wait 30 seconds and the function will be unlocked. To release standby mode, please refer to this blog.
c. If the collar still cannot work after following the above steps, please contact our after-sales team. ( support@zlolen.com )