Well, before draining and refilling the pool, I'd suggesting letting the FC drop and retest. I'd also take the water sample back to the pool store you used before as a reality check in case there is operator error in the pool testing.
I don't know how reliable any of these tests are in that chlorinated of an environment.
But I wouldn't drain and fill 6000 gallons of water from a crystal clear pool without a second test and second opinion. That's pretty drastically bad for the environment. If you don't put any tablets or stabilizer in, the CYA may drop faster than you think, or it may not. You had a green pool, not a blue pool, I'd resist taking drastic actions until you know more.