I seriously doubt any problems with the magnets, based on this being an unused unit and that using the other magnets doesn't change anything. The red magnets are slightly less strong than the black magnets. But if none work... It's possible that the reed switch is stuck. That is an easy fix, but it requires getting the Cobalt here and opening the case to solder in a replacement switch.
But before we resort to surgery, try resetting, or better yet updating the firmware, just on the off chance that long storage has left firmware in some kind of glitched state where the button press is not being seen. Instructions are here:
www.atomicaquatics.com
One other thing to try would be stacking the magnets, or using a much stronger magnet, to see if the switch has become stuck by sitting so long, and maybe a stronger magnetic field could break it loose. That's just a guess, but maybe worth a try. Let me know what you find. If none of these steps help I think the reed switch may need to be changed.
Out of curiosity, what is the serial # of this Cobalt? That lets me know when it was manufactured.
Ron