Sea Ray

A voltage meter is required to locate the problem.

The "easy" way to ID a bad door switch is to measure the DC voltage across the switch. Door closed should have full voltage (12V/24V), door open should be around 0V across the terminals.

Other tests, like does the door switch have power requires one lead (black negative lead) to be connected to a battery negative terminal, while the other lead (red positive lead) measures the DC voltage on each lead of the switch.

Given there is a problem, then the diagnosis needs to extend past normal stuff, like seeking failed connections / wiring. It may also be that the wiring diagram is helpful, but not 100% accurate. On mine, I have marked up parts where I discovered differences between the document and the actual boat wiring.

One of the things that doesn't thrill me on my 2000 380DA is that Sea Ray would jam two wires into a connector crimp barrel to permit daisy chaining lighting. That method provides functionality w/o conforming to any standards. It is possible for a conductor(s) to slip out of the connector barrel when using this method.

It my be required to remove / inspect the wiring for various fixtures and switches to locate the fault.

Inferring from the OP that more than one 24V to 12V converters exist. If so, the DC voltage in and DC voltage out for each converter should be measured.