why did my chinese waterdragon die?

Question
My brother gave me a Chinese waterdragon about a month
Ago. At the time it seemed normal and healthy but about a week
Ago trinity that was her name stopped eating.  I was sure what I
do because this was my first dragon I thought maybe she wasnt hungry.
So I waited a day still she wouldnt eat.  I noticed she was  also becoming less mobile
And darker in color. I wad worried she might be getting dehydrated so I stared sparying a good
Her cage a Good 8x a day  while I sparying the cage I noticed she was drinking. I guess what I am asking is did she die  of dehydration?

Answer
When the dragon stopped eating, that was a sign that something was wrong--she was sick.  Darkening in color is also a sign of illness and stress.

I assume she had a water dish or pool--unlike some lizards, water dragons have no problems drinking from a pool of water, and they love to swim.  If she had a water bowl, it's very unlikely that dehydration was her problem.

Without a lot more information, I couldn't guess why she died--it could have been anything from internal parasites, to an infection, to wrong temperatures, hypocalcemia...there is a list of possibilities.

Disinfect absolutely everything, and throw away what you can't disinfect, if you intend to get another reptile.  If a reptile stops eating and its behavior changes, take it to a vet with reptile experience immediately.  By the time they show signs of illness, reptiles are often very ill.  If they are taken for treatment as soon as signs appear, however, most illnesses can be successfully treated.