Congratulations @BearWithBeard, that's a great achievement, especially from someone supposed to be a "novice". I'm sure many can learn from your lessons, the most important one to me is "don't rush it", it goes with "triple check schematic then board", "unit test your components" and "don't finish late at night". Else you will probably end up with mistakes on PCB and a lot of wasted time. For reverse polarity protection, I think this is the more simple solution: https://forum.mysensors.org/topic/5478/how-to-get-longest-battery-life/25