There are several parts we need to troubleshoot.
1. Connection or power issue.
Please unplug and re-plug all the cables carefully.
try both the side port and the GPS port.
unplug the rear or interior cam, only try the main body,
use the Mini cable and power the cam using a home socket or power bank.
2. SD card issue
Pulling out the SD card or try a new card,
Below are the cards we recommend,
3. firmware or hardware issue,
Try to update the firmware and reset the cam,
If it still fails, the cam may need to be replaced.