No crank

It all started a couple weeks ago when I turned the key to start it and nothing happened. No noise or anything. I tried again and it started up. It was such a small thing that I got home, got busy, and forgot all about it. Took it to Home Depot the next day and when I went to leave it wouldn't start. No power to radio or anything either. Dad jumped me and we got it home. After some YouTube and Jeep forum diagnosis I replaced the starter. Started up and I took it to small group that night. On my way home the 'check gauges' light came on and I noticed my battery gauge was pegged at 19v. I've cleaned terminals, had the battery/alternator tested and they both passed. On my drive to test those (20 miles round-trip) the battery read normal at all times. A friend suggested the ignition switch, and after finding a YouTube video on that, it seemed like a likely solution. So I replaced the switch and the ignition switch actuator pin. Went to start it and nothing happened. No power. When I pull the positive cable and reconnect I get power back, but when I turn the key I get one click and then the power cuts off. I've looked at all my wiring and everything seems tight in all directions. I've tried starting in neutral and still get the same results. Based on another friend's suggestion, I've done a voltage drop test and checked the fusible link, all checked okay. This is all my first attempt at being my own mechanic beyond an oil change, so when I say that I've checked some of these things, there's a chance I missed something that a more knowledgeable person would have seen, or simply did it wrong. With it powering back up after I play with the connection it makes me feel like it could be there. But I'm just trying to be smart before spending more money.