My first anemone was a gbta and it floated around and never found a spot, barely opened up, closed, and then died. I think it was unhealthy when I bought it.
If it's mouth is opened and it smells, it is dead. GBTAs need good lighting too. Open up the hood and smell the water. Leave it alone for a few weeks to let it adjust. Then, you can think about moving it to a better spot. If you mess with it now, it will get stressed and die.