If RunCam 2's electricity is cut off suddenly, it might be caused by bad connection of battery. Please try the steps below.
1. Attach adhesive tape to the back side(the side without RunCam logo) of the battery. It can make the connection better.
2. Check 3 metal shrapnel connectors on the battery. If the gap between them is large, please make them closer with tweezers.
3. Please screw down the screws on the back cover and check if the battery pins on the PCB fell off and clean them.
If the problem happens still, please show us your order invoice including the order date and clear pictures of your camera by all angels.
This solved the "won't turn on" issue for me. This did happen after only using the camera one time, and is a concern.