NVR Stopped recognising 2 out of 3 cameras

[Karthik0108]

Hi I have an unbranded "Secure vision" IP CAmera with NVR setup, two of them have stopped showing in my devices list, auto add, refreshing, deleting, factory reset(on software) doesn't help... tried doing manual reset, cant find the button, the PCB doesn't resemble any of the ones available online..cant guess which points to "short" either.. can some help me here please..adding pics of the opened up camera.
Thanks in advance..

T