The trunk has water inside and now the car will not start. Is there a drain plug?

there is normally a plug under the spare tire in the back..why is water getting into the trunk that badly??? weatherstripping bad or missing?? if no plug can be found..simply drive a nail or a punch through the sheet metal to drain.. ONLY IF THE GAS TANK IS NOT UNDER THE TRUNK!!!!

The moisture in the trunk is coming through into the car with air movement, since the trunk is not air tight to the car interior.

Let's do the trunk first.
Remove the spare tire and carpet and all else in the trunk and dry it out. I would used small space heater or a blow dryer or anything else that will heat and dry the air. If you want to fix the water leak, you will need to find out where it coming from.
The most common place is the gasket around the trunk lid.
After that, a rust hole somewhere in the trunk.
You may find a new gasket hard to find, and if you do, not easy to replace as well.
Finding a rust hole might require you to take a strong light and have a helper to look either inside when you have the light outside, or outside when you have the light inside the trunk, (night works best).
On older cars, I have often made a permanent hole in the lowest part of the trunk to drain out water leaks.
Make a hole about 1/2" diameter of more, so it won't plug up. There are sometimes rubber or plastic plugs you can remove to drain the trunk as well.
Make it so stuff you replace into the trunk will not cover that hole. Carpet holds water, so you may choose to put a new piece of something in there, or nothing.
Read the instructions below on usuing "Damp-Rid" plastic buckets in your trunk.

Now lets go inside the car.
I recommend you dry out the inside with a space heater or blow dryer as well, for a day or a few days.
Then,
Lumber yards and hardware stores and such places sell a small bucket of stuff called "Damp Rid"" This is plastic tub full of white crystals that absorb water out of the air. Put one or two of these in your car on the floor of the back seat and maybe the passenger's front seat. Follow instruction on the container, and they will remove moisture from inside your car.
NOTE: You must be careful because they work with the top open, and therefore will spill accumulated water when you start and move the car, they'll tip over. If you put them in the trunk, don't forget them there.

Could be water is pooling inside one side of your trunk from a loose sunroof drain hose or power antenna drain hose. Check the drain hoses to make sure they are draining water down under the car and not into the trunk.

Check the trunk rubber for damage and/or improper mounting. There will ordinarily be drain holes in the area where the tail light assemblies mount to the back of the car. If they are plugged up, the water will have nowhere to go when it rains, and will seep through the gasket between the tail light housings and the body metal. If unable to find the problem, have someone soak the back of the car in the trunk / tail light area with a garden hose, and watch for water intrusion from inside the trunk with a flashlight (hopefully, the rear seat backs flip down so you can gain access to the trunk from inside the car). Good luck!

Which one? If you have water in the trunk, remove the spare and the liner and you'll find two drain plugs. If you have water in the front, check the inside of the moonroof for the drain plugs.

this water good be coming from anywhere, the trunk gasket or theres a floor plug thats missing or it could be coming in from the heater drain if its plugged, you would need to use a water hose at start spraying in one area at a time until you see water coming inside.

If you remove the carpet, you will find rubber plugs there that plug the drain holes in the floor. May be that one of them has dropped. And then the water flows every where.

check the floor and the trunk for water,it sounds like something is damp,or got wet. start there, also make sure heaterbox drain is clear, drain sometimes plugs up and the condenstion water then fills in the box and leaks into pass/side floor instead of draining outside. hope this helps.

These cars (Sevilles) have a problem with water in the trunk. It comes from clogged sunroof drains. There are 4 of them. One in each I-Pillar and one on each side that travel back toward the trunk. They can get clogged, and my mechanic tells me that this car has had issues with this.

same problem happened to my 2005 bonneville. inside the trunk and behind the carpet covering the wheel wells there are two water drain tubes. these tubes run down the inside of the "c" pillar and drain the water from the sunroof. they make a 90 degree bend at the bottom back of the wheel well(inside the trunk) and fit inside a round rubber tube/grommet at both of the rear wheel wells that lets the water drain outside.either the plastic 90 degree tube has come out of the rubber tube/grommet or the drain tube could be plugged up with debris. also make sure the two round rubber tube/grommets are installed correctly and seal the hole going through the trunk to the outside of each wheel well. this is of course only for those bonnevilles that have a factory sun/moon roof.