There are mainly two steps to troubleshoot the issue,
1. Check the connection,
please unplug and replug all original cables carefully again,
We also suggest you try the unplug the rear cam(if you have) and use the short cable and home socket to test,
2. Format the card or use a new card.
Below are the cards we recommend, you shall try.
You shall reset the cam and update the firmware as last resort.
if all fails, you shall contact customer service for technical support.
② Email： firstname.lastname@example.org