1. Please make sure Bluetooth is turned on in the "Quick Switch" or "Control Center" page of your phone, and then connect the printer in the "Main Printer" application.
2. Please make sure that you have obtained all permissions when downloading and installing the application, if not, please enable it in the "Settings" of the phone system.
3. If none of the above methods work, use a thimble or similar tool to poke the reset hole next to the power port and try to restart the printer and phone.

1. Confirm whether the paper roll is thermal paper: Thermal paper can only be printed on one side. Use your fingernail or any other sharp object to scrape the paper. If any color appears on the paper, it is thermal paper. Install this side facing the print head.
2. Clean the print head using an alcohol cotton pad. Make sure there is no dirt or adhesive residue on the print head. Allow the print head to air dry and then try printing again.