Over the last several years I’ve found too many failed circuit boards on Rheem/Ruud (specifically) gas package units. The solder on the back of the 9 or 12 pin molex plug cracks and the solder disappears. I don’t know if it’s overheating and vaporizing or… The cracking makes sense because package units are out in the weather, I’m in Tucson Arizona where the summers are 120° and winters get down into the 20’s on occasion. I’ve made temporary repairs by squeezing the pins with needle nose pliers long enough to get a replacement board. I could solder them but there’s a bit of liability there.
I’ve also found the same on Goodman furnaces, and Lennox, but it’s always on the back of the molex plug. Which is typically a safety circuit, or limit.