Clothes dryer fix: any advice?

My son is good with repairs, so I let him tackle the clothes dryer (Kenmore Elite) when the heating unit failed. He narrowed the problem down to a thermistor, Whirlpool P/N 3976615. I ordered one.

He put it in and said it blew right away. There’s a problem elsewhere. I ordered 4 more thermistors, brand name Blue Stars. The first one I got was I guess Brand X.

The repair guy I called won’t come unless the dryer is back in its prior state so he can diagnose. Too late, I’m afraid. It’s completely dismantled now.

Am I going to have to purchase a whole new dryer for a ten-cent part that cost me five dollars? Any advice? <—(Advice pertaining to the fix, please, and not to the wisdom of allowing a helpful son to try his hand.)