water leak into the trunk area 2016 Prius by vent

bought 2016 prius 3 with sunroof around 35k miles
found some water in both side of the trunk, some investigation and found a small crack in the back right under the light from a possible minor accident that was not fixed well. fill that up with body sealer and most of the problem went away.. there was some water coming in from on top of the black vent in the back , added some sealer and silicone from outside and that stopped the leak from the top of the vent....
poured bunch of water and everything seemed dry... still could not figure out why there was water on the left side ...
closed it up , 2 days later after car was parked under the rain checked the back again and there is water on both side and some in the spare wheel well..
it seems like water coming in from under the black air vent and from behind this metal body panel in the picture.
the sunroof vents seam to drain fine and could not replicate the water leak by pouring water on the car...
so it seams the car has a right side back accident and the bumper was repaired in the back but I can not figure out how water gets to the air vent and behind that metal body part...

any advice on what this could be would be greatly appreciated.

 

so the gasket was a bit lose, will seal it with some sort of glue or silicone to stay in place,
found leaks from the top part of the Brake light, the little guide that holds the back light was lose and letting in water.
the vent, I could not figure out, poured water all over it and nothing went in.
the brake light screws were a bit lose on one side and leaking a bit
will silicone these and test the car again..

there was a little sensor like thing that broke as we were inspecting stuff.. in the picture wondering what that is.. just says Denso on it.

 

these screws were not tight and water was getting behind them a bit

 

siliconed up everything I could find in the back of the car and hose it down.. no water came in
drove it to work and later on in the day I see few dropps in the back on both sides..
very little water but I can not figure out where they came from

 

I am thinking the moonroof drain hose might not be fully tight and the water that seats in there splashes out when I drive.. it is not much but I need a better way to trace the moistures or the water drips, I can silicone that tube in place in to the plug to rule that out I guess.

the car had body work on the left rear , but the water is on both side

 

so it is not the sunroof or the drains...
water comes in from a crack in the body probably from the rear ended accident that this car had before.
last time I took off the bumper and could not see any crack behind the bumper in the body.. I even poured lot of water there and nothing..
Maybe the screw holes that hold the bumper..

this is driving me nuts

 

it was a dealer sale, and he is okay for me to bring the car back to check it. it is just 3 hours drive each way to the dealer... and if the issues is not resolved there is so many trips I can take.. it is a whole day and gas and tolls in costs...
Henece the reason I am trying to figure it out as much as possible on my own.. taking it back would be the final choice

 

it is a 2016 prius 3 with 35K miles at 16$K, it was a great deal... so it is not worth returning the car
not certified..
anyway I was looking for technical data to help find the leak...
I guess I have to spend more time in detail on it and slowly rule things out

the issue is when the leak comes from under a panel in the car that you can not see the source and the car is so countoured and has so many ups and downs that the water can be coming from any point above the leak I see inside..
dont think there is any technical document showing the layers of the body in the back so I can get a better idea

 

there is no way to check the roof rails without getting the rear wet .. I guess I will have to rip those roof rails off and check under .. not too hard right? just clips and pull it off?

 

as the weather got better, I took apart every last bit of the back of the car and silicones it up and still saw the leak, then took apart the whole trunk door and found huge gaps and leak... the trunk door was not repaired well after the accident probably ... much silicone later the problem is gone