Why Fluorescent light cause power trip at home?

Last year end,our area hit by continuous rain for 2 weeks.
And then my 2 backyard lights cannot be turn ON. If switch ON,the whole house power trip.
I suspect due to heavy down pour and water leak to my backyard roof.

Since then I am not able to used for the past 3 months. I did not put effort and thought on how to fix it.

Only yesterday, I want to take a look on what happen to the lights.

Problem statement:
Power trip whenever the light is switch ON.

Caused:
Since I have 2 fluorescent light at backyard and control by one switch,I have to isolate which light caused the problem.
In order to caused power trip, either one of them is causing it.
But if you look at the component of the Fluorescent Light, the power coming to the Ballast first. So I am highly suspect is the balast that causing the power trip.

How to Replace the Ballast in a Fluorescent Light?

1. Turn the light off at the switch, as well as at the circuit breaker.
2. Remove the Tube (Picture 1), you will see 2 screw on the back plate.
3. Remove both screw and you will see the Ballast and wiring.
4. Closer look at Picture 3.
5. Remove the wiring at that connect to the Ballast
6. Remove the Ballast and replaced with a new one
7. Then connect back the wiring
8. Cover back the backplate
9. Put back the tube.
10. Switch on the light and circuit breaker

Your light should be back to normal.