The cable for the remote in the trunk came loose, now the trunk won't open with either the key or the button on the door. what to do?

The key should still open the trunk even if the pop trunk isnt working,sometimes the lock gets stuck from not using the key and always using the button, try some wd40 spary in the trunk key hole and then work the key in and out a few times even try a spare key then spray it again anf work the key but this time turn it side to side like your trying to open the trunk, time may take so time but works, i sometimes spray it good and let sit for a day before working the key in the lock. hope this is helpfful.

You should be able to go in through the back seat. It will be a chore to remove the seat, but will probably be the only way to get in there. There is a safety release cable in the trunk that will opne it the lid for you once you get inside