Man your problem is a root issue, I assure you. Those roots are very unhealthy, and look to be the victim of root rot or a similar disorder. Heres what I would do.
1.Get some h2o2 from your hydro store asap. This is typically 35-40% h2o2 (unlike the 3% in the brown bottles). Ive heard that the stuff in brown bottles isnt good for plants, but honestly ive never tried it so I dont know.
2. Empty your rez, clean it out good. Make sure you get any salt buildups or bacterial growth out of there.
3. Buy a small airstone from walmart, add it to your reservoir.
4. Refill your rez with the new airstone added, and mix in 1 1/2 tablespoons of that peroxide per gallon of water you add.
5. Make sure theres no light leeks in your bucket, this promotes bacterial growth.
Your plant isnt dead, but if its roots dont pep up then it most certainly will die. You can trim the roots also, to make cleaning the remaining ones easier. This will decrease your yield in the end, but make it easier for the roots that are left to stay alive. If you do trim them, make sure you dont go overboard, and just trim around the edges.
To prevent this in the future, you can simply add peroxide to your reservoir from now on. Or get some beneficial microbes to add to your nutrient solution (many companies make them, check your store, I like AN's but there are plenty of options). If you do add beneficial microbes, dont use h202, as it will kill them.
Make sure you get around the base of your plant covered with something, alluminum foil or mylar works well. Idk what that white shit was but it didnt look good lol.
EDIT: Sorry this happened on your bday man =(
Also, to Brick Top (love that movie btw), I believe most people who use hydroponic setups flush by emptying their reservoir, cleaning it, and refilling it with plain PH balanced water. In a recirculating system this typically flushes the roots in a few hours.