Auris Hybrid - water in boot - strange fixing

[Kojac]

Charged Battery, placing it back in the car &:

A) Car hasn't been washed in a year.

B) What is this fixing/joint for.

C) How can it just spontaneously start leaking

D) How to fix this

Going through a hard time with this car. Bear with me, the support is genuinely appreciated.

 

K.

[TonyHSD]

Rear lights clusters, you need to buy new seals . Remove clusters out of the car and carefully and thoroughly clean them and clean the body work where they fit into from debris, dust, leafs,. Replace seals and fit them back in. Do not over tight nuts. If you have no new seals you can use silicone sealant but it’s will make them ultra difficult to remove in the future if need to. 
This is common fault on these and most other Toyota cars. 

[xrhstosgr]

You can use a milder form of silicone that is equally waterproof, which you will be able to remove whenever you need without a problem

[Kojac]

Can anyone point me to a guide, on how to remove the rear lights, without damaging anything?

What's the proper procedure?

[AisinW]

Yes, it is usually rear light cluster seals or just some debres that trap water. 

I clean the water channel regularly in summer because of tons of dirt and pollen there.  

We do not have problems like cracked roof in Prius gen 2. JBwelder original epoxy can fix everything solid and hard.