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The bilge should be wired directly to the battery with an inline fuse.

With the engine off and battery switch off, remove and clean the battery terminals for all batteries. Reinstall.

Retest.

Power on, restart engine. Test each accessory.

if no go,

Turn all the accessories off, engine off, battery on.
Cycle the breakers. Off then back on.

Test each accessory with the engine off. Start engine. Test each accessory.

Report back