Also, interesting lack of flux removal after the through-hole soldering. What are peoples opinions of this?
*Very* disappointing!
I've "repaired" a number of pieces of consumer gear simply by cleaning the flux off. It's hygroscopic so in humid environments it's a guaranteed recipe for trouble. This is especially true with low voltage logic.
My Walmart brand microwave gets all stressed out when the humidity is high for an extended period. I've not opened it up. The air dried out and it calmed down and behaved properly. I'll have to take it apart and clean it eventually.