if the turn sig works, there's nothing wrong at the light - if the turn sig keeps workin when you hit the brake, that's how it's supposed to be - the brake wire goes from the power supply, to the brake light actuator switch, to the turn switch, and when one signal is on, that interrupts that brake signal, supplying it's own power [brake applied or not], and it uses the brake light wires from the column to the tail
I'd start at the front and see if there's power to the brake light actuator sw [mechanical that the pedal arm controls, or on the master cyl], if that power isn't getting to the turn sw, no brake lights - having a factory wire diagram is a real help - the fact that you also have no tail lights makes it seem you have a bad connector ahead of the turn signal
Bill