Wow, I just talked to Garrett, that was a lot less painful than I expected it to be.
Told them the problem, and that I had tried with 3 coils, 2 headphones, 3 battery packs, and the problem is definitely the control box, and said hopefully they can send me a new control box. She instantly agreed and said she will have UPS come by my house tomorrow to pick up the control box, then when she gets the tracking number, she will ship out a new control box right away, and hopefully it will arrive by monday.
Awesome!
Even though I'm frustrated that I haven't been able to detect for 2 months, I can't be mad at Garrett for it, that is some amazing Customer Service.