By looking at the engine parts, there is no compression release. So Compression can be tested by removing the glow plugs and using an adapter to test compression. But are the glow plugs working and heating the cylinders when glow plug is selected? HAve the valves been checked? If valve was open, on cylinders, you would have no compression.?
Call not being completed! If you have no compression, it is a result of the cylinder itself. The only thing that determines the compression is the pistons and rings and the valves. Nothing Else will affect compression! That is why the compression needs to be checked or at least check the valves, for clearnace.
did valves have clearance? If valves had clearance, then you may have cylinder damage. Could there have been water enter cylinders when the manifold was off?