The biggest issue with a "dead" coil is due to the positive pin in the coil not making contact with the positive pin in the battery.  To fix, remove the coil from the base, holding it right-side-up.  At the very bottom of the coil is a rubber gasket with a small piece of metal below it.  Pull down on that small piece of metal until it extends about 1/2 mm.  Place the coil back into the base of the clearomizer/tank, fill and enjoy!