I do not have access to Samsung tech data so do not have a wiring diagram so I can only give generalized info.

The heating coils are probably OK.
It would be best to check them using resistance Most coils are in the 8 to 12 ohm range.
Be sure to unplug the unit when doing this.

Using Neutral (ground) as the reference side when checking out a heater circuit can be confusing because Neutral is not part of the circuit. The circuit is from L1 to L2.
You do not know if you are measuring L1 or L2.
So lets say the L1 side is OK and L2 is open. When you measure on the L1 side of the heater you will measure 120 volts. but you will also measure 120 volts (L1) on the L2 side of the heater since the heater has continuity. If you measure across the heater you get 0 volts.
Now lets say that both L! and L2 are OK. You will measure 120 volts on the L1 side of the heater and also 120 volts on the L2 side of the heater but when you measure across the heater you now get 240 volts.

I do not know how much electrical you know so perhaps the below will be helpful.
Your electrical is actually two 120 volt supplies which share a common Neutral but they are 180 degrees out of phase. So when one is at positive 120 volts the other is at negative 120 volts when referenced to Neutral. When you measure across them you get the 240 volts.

I do not have a wiring diagram so can only guess.

Since the heaters, thermistors and thermostats are all OK then odds are that is is a board.
I did find a parts breakdown diagram.
It shows a board monted on the left hand side with the relays on it. It is the most likely culprit5 not the control panel.

There is also another possibility but I do not know if this unit has it.

On most units there are two centrifugal switches. They close when the motor gets close to operating speed. One of them switches in the heater. This ensures that there is air flow before the heat comes on.

To tie this one up for others, here's what was wrong.

The control board was NOT the problem. The problem was the centrifugal switch on the motor. There a two contactor switches within this switch assembly. One switch passes 120V power to one side of the heater element while the other switch passes the neutral power leg to the water values and then on to the control board. Because the switch was passing 120V power to the heater element I "assumed" the switch was not the problem.

Turns out the contact button on the switch had burnt off and wasn't passing the neutral leg through. This caused the dryer to think the drum wasn't turning and wouldn't let the heater relays on the control board to open. In test mode the heater would work but it only kicks on the heater for 3 seconds and doesn't care about other sensors for the test. Control board just wants to determine if the heater works properly.

The bummer news is that Samsung no longer sells the switch separately and makes you buy a whole new motor with the switch attached. Nice way to make some money.

Appliance Parts Pros are great! Shipped parts quickly and even allowed me to return the heater element which I never ended up using. Will definitely buy from them again. Thanks to Denman for the help as well.

Many Thanks Scott! Got my daughter's dryer fixed and working well. Your post above got me on the right track. It was the centrifugal switch on the motor. It was making the circuit for the 120volt L2 leg, but not the neutral circuit for the feedback to the control board. I pulled the switch and found it to be a very simple copper tab switch. The contact button on the copper tab had fallen out and would not make contact. Looked like the contact button was peened into place, but not enough... I was able to replace the contact button with a small stainless machine screw and peen into place, grind to shape, and reinstall everything. Now it works great. Not only did we save buying a new motor assy (180 dollars) I installed the old control board and display board and everything works fine. I am a little puzzled about one thing. This can't be a unique problem. The control boards are out of stock everywhere, the motor assemblies too. I can't believe this is not pointed out more buy all the You-Tube repair videos and website help sections.... If you are interested on how I rebuilt the motor switch, I took a few pictures. Thanks again!!