Thanks for the feedback! The solder bridge was not intentional, but that was not causing the issues. I finally received my latest PCB version in the mail. I get them from a company called Sunstone Circuits. They aren’t the cheapest, but I am in the U.S. and I’m not comfortable sending my propriety stuff out to PCBWAY in China, even though they are dirt cheap. You don’t think the PCB is good quality?
So I put this one together today and it actually works! I put Kapton tape over the BAT- to protect this from accidental solder flow from the BAT+. I know some XIAO purists here won’t like not using the BAT-, but it is connected to the GND pin. I am not using the built in charger anyway because 100ma is too small for my battery. So I fluxed a wire (without insulation), soldered it to the BAT+ pad on the XIAO, then passed the wire through through the now GIANT BAT+ PTH and inserted the XIAO into the PCB, then solder the other end of the wire to the plating in the PTH. This works with no issues! If anyone wants the Fusion 360 component, I’ll try to figure out how to post it on Github.
You suggest doing SMD, i don’t know much about that, don’t you need a reflow oven for that or something? And yes, my soldering is terrible 
, no offense taken!
Good luck with your product, sounds great and I hope you make lots of $$$. It’s hard bringing new products to market. And I know all about patent attorneys being expensive, I actually am one!