SHP-DH538 - How to change the master PIN code

1. Unlock and open the door
2. Take the battery cover off
3. Press the [REG] button to start registration : Ding dong
4. Enter the current master PIN code (default is 1234) + *
   • Success : Ding Dong Deng
   • Fail : DingdongDingdong
5. Press 0 + * : Ding dong
6. Enter the new master PIN code (4-12 digits) + *
   • Success : Ding Dong Deng
   • Fail : DingdongDingdong