Air Locked??

The conditions sound right to cause an airlock. It isn't just the pump. An airlock involves the pump, lines, and injectors, as a whole. How you manage it depends on how much you want to beat up your starting and charging system. You could charge, crank, charge, crank, etc, and it will eventually start (if everything else it healthy). It may take a long time, and place a lot of load and wear on the starting and charging system. Or, lighten the load and shorten the time. Begin with fully charge batteries (and keep them charged throughout the process), then remove the glow plugs (only those you can reach, don't bother with #8, and possibly #6, if it's difficult). Removing as many as you can lightens the cranking load accordingly, and also allows for faster cranking. Loosen the injector line nuts at the injectors you can reach without too much difficulty. All of them is not necessary. If you want less mess, place rags opposite the empty glow plug holes, not against the holes, but not too far away. Secure the rags so they won't get wrapped up in something else (belt, etc). Key on and crank the starter until you get fuel wetness at one or two fuel injector line nuts. Crank for only 20 seconds at a time, and allow a few minutes between crank cycles (don't overheat the starter). Tighten all fuel injector lines. Crank again until fuel mists from many/most of the glow plug holes. It should within a couple cranking cycles. Replace the glow plugs and connectors, and secure everything under the hood, ready to run. It should start. It may run rough for a bit while it purges the remaining air, but it should clear up in a few minutes, at most. Adding some throttle helps speed it along.

In the future, your first and last step during a filter service (or any process that may introduce air into the system), is disconnect/reconnect the ESS solenoid connector (solenoid on top of the injection pump, vertical cylinder on the DS4 or 4911). This will prevent air intrusion into the injection pump. Don't reconnect it until the service is complete and the fuel system is completely bled. Air intrusion will be minimal, and may cause only a hiccup.