It seems as though you have pulled on the cable when removeing the BNC connector from the old recorder this may have dammaged the connection in the bnc
replacing the bnc connector on the coax cable will normally cure the problem.
I would also check you have not removed or disconnected the power to the cameras this may be either 12v dc 24v ac or 240v ac depending on the type of camera.
replacing the bnc connector on the coax cable will normally cure the problem.
I would also check you have not removed or disconnected the power to the cameras this may be either 12v dc 24v ac or 240v ac depending on the type of camera.