What exactly does"the engines cranks attempts to turn over" mean and where is the battery "going" to?

If you would be more specific with your description of your problem, I could be more specific with my answer.

Does the starter crank the engine at the same speed (RPM) it always did? If not, then the problem is the battery, starter, cable connections or corroded battery terminals. The starter should crank the engine at 100 RPM or more.

Does the engine fire at all? If it does, the glow plugs are working but not enough fuel is being delivered to the cylinders. It is unlikely that that this would happen by just shutting off the engine and then it wouldn't start on the next try. It might have happened when you took the fuel system apart when you replaced the filters.

Do you have a manual transmission? Do you have a hill where you could try a roll start? If this starts the engine, it would eliminate the fuel and GP problems and point to the starter or battery.

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