Just FYI- Techs often go for main board (PCB) when they are either uninformed or don't know what to do. I see it in baby techs routinely, most experienced techs know how to check for PCB functions. But in general if ignitor glows the board is trying to ignite and probably ok.

So 1st he/she needs to determine if coils are being powered when flame sensor is satisfied. Both coils, and all 3 circuits in them because one has 2 coils inside. If they are all energized at the same time they will pull both sides of the valve open and gas will flow.

My off the cuff guess is that you need a new motor. I'd need a wiring diagram to tell you if power to the coils passes through the motor as it does in their elec dryers; they have had some issues with that circuit and it drove us crazy diagnosing it initially. The centrifugal switch on the motor fails to close and power the elements (in elec). It's the same motor so probably similar wiring. I'll try to find a wiring diagram to see if they wire the valve that way. There may actually be one taped to back of the dryer in a bag.

I'm sure your dryer is repairable, once diagnosed properly; but if HD will swap it out go for it. I'm assuming it is either under 1yr old or you bought a service contract?

Here's a diagram on this site of different samsung dryer and they do run the neutral for coils through the motor on this model, likely on yours also. It's a safety feature, if motor stops so does heating.
Parts for Samsung DV3C6BGW/XAA: Laundry Wiring Information Parts - AppliancePartsPros.com

Oh I misread, thought it lit up. Did he test the thermal fuse on back of blower housing? On electric it stops motor but on gas it is in series with the burner usually.

Still I'd suspect the motor centrifugal switch is likely. It may pass continuity test but have burnt contacts internally that do not pass current. I've personally changed dozens for no heat situations that test OK static but not with load. That switch provides neutral to the burner; no neutral, no igniter...

Wire harness is a last resort for us. Once in a great while it solves it but I'd need to see an open wire and be able to verify that it is the cause.

Good luck. Let us know...

Geez I assumed this one had been fixed. A lot of technicians are afraid of gas or just unfamiliar with it. Or simply unable to read a wiring diagram.

My employer no longer deals with Asurion. But I seem to remember they would replace machines if they were unable to get them fixed. If they fail again, and they will if they are trying the thermistor, I would start raising a little hell with Asurion and if nothing else request a different servicer.