Clearly its a mobo fault. I assume you didn't perform any undervolt or overclock activity right?
The nb still under warranty right? In that case just insist on warranty. Keep in mind warranty is not an one to one exchange.
Did they provide any prove of no fault found from their end to refuse warranty?
I please tell me you did not play on bed or turn down fan speed while under load.

Did they provide any screen shot? If it has no problem on their side, is there any thing might be wrong on your side? Have you check during problem if the power adapter is plug in and has power? Did you use external monitor to confirm and did the issue only happen with external monitor?
Refusing warranty is not a small thing for me. So it is likely their tech is being honest with you.
If you have any screen shot, I recommend you to provide it to them and insist on warranty regardless of their diagnostic conclusion. But keep in mind warranty is not an one to one, so adjust your expectation.
If you have a second screen, I recommend to open a monitoring software during load such as hwmonitor to see if it overheat. Also disable auto restarts in advance system properties so that you can see the error code if any. Capture any prove on your side and you should be able to ask for a warranty. Provided you can wait. One to one after 5 months is not likely going to happen.

Warranty might not equals to a replacement. However, I would encourage ts to insists on warranty from the retailer.

Have you read through any of the Asus, msi, global brand forums lol. What you expect from a local company that did not manufacture anything that they sell while even the international brands have so many complains.
I believe everything on the market has its purpose and reason to be there. One needs to understand what ones buy and what to expect.
I personally would not buy from these local brand. Didnt even know pc shops have boutique style retail before this.
Why ts don't buy from lowyat retailers? Sure they have complains too, but at least its cheaper right?

Like I mentioned, have you check if adapter has power? Can you confirm if the issue only happen when the screen is connected? Also try to use hwmonitor to see if it overheats.
It is likely that the tech on their side is honest with you if they have picture to prove its no fault found on their end.
So if you have concluded that it is surely not your end problem, just formally submit your pictures and insists on warranty from them provided that you did not insists them to give you a new one on the spot.
For me, if you have picture of no nvidia in device manager, it should be enough to ask for warranty. Unless your nb is those type that has detactable gpu.

Usually the dispute starts when customer ask for one to one on the spot. Warranty does not warrants an one to one in most cases in computer. Just a guess on my part. Otherwise, I do think ts should push for warranty.

If you have prove of fault, and they refuse warranty, I guess its only fair to disclose their name. But I suggest to only do it after you have aquire all services from them. You know what they say about annoying the people who handles your food right? lol

1 to 1 or refund after 5 months... hmm, seems unlikely. You know nuclear buttons are often a mutual thing right?
Since you mentioned they have prove the nb is OK to you before, maybe better to check again or send to a different shop for a second opinion. Even if you do want to push the nuclear button, do it with as much data on your hand as possible instead of acting on an emotional note.

Who in the right mind that has a degree want to work as a low pay tech lol. Of course techs in retail level are spm grads lar.

Hmm, most nb gpu is soldered on to mobo, so its technically not wrong for the tech to say its mobo fault, unless its those detachable one.
And most retail shop tech operate on board level instead of component or circuit level. Means if gpu on mobo fault, they swap the mobo.

Other than labor, I would think the cost is bear by supplier or manufacturer. They just have to claim it from their supplier, so I don't see why they would refuse a warranty unless ts ask for one to one on the spot.

For a gaming nb that has dual gpu, intel and nvidia, you should not need to manually switch it for it to work. Even if you can fix it by manually switch it in bios to nvidia only mode, it means something is wrong already.
I recommend you to just submit all your picture to them and formally ask for a warranty from supplier or manufacturer side. Sau that you insists on warranty even their side has no fault found. Just give them time to arrange replacement of the mobo if your gpu is not detachable one.
Since you have already spend so much time, I guess its just right if you push the nuclear button on this one. But do make sure there is nothing else you want from them, or other things that still can be bring to bear to resolve it.

Can one. Ask the shop to run diagnostic and temperature monitoring. Diagnostic can be perform without opening the nb. They dont even need to do very detail work, ts intention now is to push the nuclear button, so ts just need a diagnostic service receipt to help prove his case.
Also if another shop cannot find fault, then it could be the fault is on ts side. Which can help to narrow down the source of the issue.
Ultimately, I think the shop should at least try to send for warranty on their side before it comes to this...

It is always ok to get as much information as you can before making a decision, just ask the shop to run diagnostic test to check if it is OK or not without opening the nb.
Most shop would run typical diagnostic without plug in a second screen. Ask them to plug in a second screen, have hwmonitor and other monitoring software to diagnos. And provide print screen of test result. Could be done in a few hours, also you might want them to run it overnight. If problem didn't occur.

This post has been edited by samftrmd: Mar 3 2021, 01:51 PM

If still possible at this point, insists on a new mobo form them.

I have diagnos my fare share of nvme issue. Soeed is faster, but heat is not better. Also given the location of the nvme port are mostly near heat sink or gpu, better use sata ssd, not that the speed is noticeable in real world usage.

Use edge jer lar.