Hey Brach, thanks for the quick reply on such an old thread. I am using lead free solder. When reflowing the resistors I did turn up the heat some more and did get better results. I also do have flux (in syringe form!) and used it to help reflow the resistors. I checked for continuity on the isp and didn’t find any pins bridged, but I did not test for unwanted grounding. When flashing, the pc did say it successfully connected and successfully flashed. When I get home tonight I will go ahead and remove excess solder and reflow all joints and update you. Thank you again for the guidance!