I don't think you get 12v DC out of the coil so using a testlight is not what you want to do on the plug end of your coil. You'll need a spark tester, you can get them for $5 to $10 at vato-zone.
That loose wire looks like a shield. It's there to block any RF interference on your signal wires. A shield can only function if it is connected to ground on ONLY ONE END. If you don't have a multi-meter you can check if that shield is grounded on the other end by clipping your test light to battery +, and probing the shield wire. If you get a light, do not attach the loose end to ground, just wrap it around your sensor wires and tape the end in place. If you do not get a light, ground that end on the block.
Did you check your crankshaft position sensor for damage? Camshaft position sensor? One of those sensors could have failed and may cause a no spark condition. Very unlikely that more than 1 coil failed at once, so I would lean towards replacing the crankshaft position sensor first if you know you have a good power & gnd to that sensor and the camshaft sensor.
Do you have the ability to grab the CEL codes?