What should I do if Xiaomi Smart Kids Watch cannot recognize the SIM card?

Please follow the below method to troubleshoot:
Make sure you are using a standard Nano-SIM card, do not use a cut card or non-standard Nano-SIM card. Otherwise, the SIM card may not be inserted or removed properly and the card slot may be damaged, thus affecting the use of the device;
Confirm whether the SIM card is installed correctly;
Try restarting the watch several times;
Try to replace the SIM card;
If none of the above operations can solve the problem, we recommend applying for after-sales testing.