It's normal for the device to become a little warm while using your wireless charger, but if it becomes hot to the point that it is uncomfortable to touch, then it is likely a defect. 

Here are some troubleshooting tips that may help identify and resolve the problem:

• Please confirm that your device supports wireless charging.
• Remove the protective case from your device if you have one.
• Try using a Quick Charge or Power Delivery (9V/2A) wall charger. The iPhone’s 5V/1A stock charger and computer USB ports do not provide sufficient power.
• Try using a different cable and outlet.

 If you’re still having problems with your wireless charging speed, you can contact MyAnker Customer Support for further assistance.