Omission on my part: Meant to include battery as a possible cause, per 02 LW300.
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Current is required to spin the starter motor when it is engaged with the engine's flywheel. ALOT of current.

All the stuff you mentioned takes a few Amps of current.

Cranking the engine over requires a peak current of SEVERAL HUNDRED AMPS.

If there is not enough current available to crank over the engine, there is likely not a high enough potential difference (aka Voltage) across the car's PCM and other computer controlled modules (like the BCM) for them to operate properly or perhaps at all.

If this is the case, the systems will not operate as designed, and trying to troubleshoot it in this state is pointless because any resulting behavior corresponds to ? since the circuits are underpowered.

When the house lights flicker and dim way low in a storm while you're using your desktop PC (with no battery backup), does it crash?
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Now you know how Passlock is SUPPOSED to work.

Next time you go to try to crank it, first whack the starter w the end of a pipe, etc -- it may be hung up. THEN

Go get a new battery; you can what-if till the cows come home, but unless you ensure everything is getting sufficient current and the proper V across it, you're throwing gasoline tipped darts over your shoulder at a spinning wheel freshly coated with White Phosphorous.

I agree, first install a new battery. It is possible to assist a low battery with a jump, I do it all the time at work. If the battery is dead, install a new battery and then find out why it went dead.