I hope you don’t have any more problems. Your right on the intermittent BS it sucks. I don’t lose any power when starting the car. If you look at my thread I posted earlier today you will see what Hyundai says it is. I can start the car now but if I shut it off and immediately try to restart it won’t. It has to sit for 15-20 minutes or longer before it will start again. Hopefully I get it fixed. Lol
I had the same problem with a 2011 Santa Fe.
Intermittent no crank and after an hour it would start and run okay.
Fact that it runs okay led me to to conclude that the BCM is not likely bad.
I had to replace the intake so I installed a starter and found the one I removed was a NAPA starter and it wasn’t that old,but replaced it anyway to rule that out.
Car has Hyundai Autostart so I had it removed thinking that was the cause and now my key fob will not lock or unlock the car. After about a week, no crank.
I talked it over with an experienced and trained diagnostic guy and he supplied me with a schematic and I zeroed in on the 4 contact clips that the relay plugged into(under hood fuse box).
I wanted to see if the terminal coming from the ECU was providing the necessary ground to activate the relay, so I shoved a wire connector ( spade) into the slot and found that it was barely making contact. To explain it a different way, the relay would not complete the circuit because there was a bad connection to the ground pin on the relay!
I used a dental tool to bend the contact clip so there is a good connection and it’s been a month since and no problem.
Journeyman mechanics run thier diagnostics and draw thier conclusions based information they get from thier diagnostic scanners, and flow charts but it’s never easy to isolate an intermittent problem. It’s easy to simply blame a component because it it’s almost impossible to thoroughly test in a mechanic stall.
From what digging I’ve done it’s obvious that this is a common problem and I hope this helps out the DIY and pros alike.