i have 4 cameras
i bought from gearbest the set
https://www.gearbest.com/surveillance-camera-system/pp_1253461.html
first i thought i put the bnc that was for camera to the dvr but this was all right
the hard dsik is ok
now i think maybe was wrong to put the bnc to the back of the dvr while this was powered on
i dont know what to do really