DC distribution panel red lamp on meaning

[AndyEss]

Well, at least you have a pretty good idea now what’s going on - and you’re learning about your boat. If you have a multimeter, you could test the float switch in place by cutting open its two wires and checking resistance with the float up and down. It sounds like it will read about zero ohms in both positions, which will confirm the switch is bad. I have no clue what to recommend for a new switch.
From xxxx’s comment, that breaker should turn on the bilge pump. Turn the breaker on and see if the bilge pump runs. If it doesn’t, the pump burned out from running dry. All you’ll need is one trip to the local WM store.