Last inquiry about Mk-160 has been resolved. It was an open solder connection. New problem with 3rd board of 3 recently purchased. This one does nothing when powered up. No light no camera no action. Only thing I can confirm is the board is seeing correct polarity, regulated 12 V DC and there is no voltage across LDR1 whether light or dark. Magnifier examination of all solder joints looks good.
Impossible to say without more details. Can be anything, most likely an assembly problem.
As you have working samples, you can compare voltages and signals.