Laptop fan not spinning.

I have an Asus Rog G771JW laptop, I had it for almost 6 months now. Lately I have been noticing that when turned on it would make a loud scraping noise that would last ~10 seconds. But yesterday the fan completly stopped (from what I can hear) only the CPU fan is spinning which is rather small and cools only the CPU, the main fan, the one that cools the GPU and instakes and exausts the air is not spinning at all. I have tried rebooting it multiple times, reinstalling and the drivers. It does not allow me to control fan speeds through BIOS or afterburner. Before doing an RMA I just wanted to check if I'm missing something, I use the laptop for gaming but I'm unable to because the whole system throttles in a matter of seconds after running any game.

I appreciate any help I can get, if not I'll just RMA it.

Give it a good cleaning. Probably full of lint.

Is it safe to open the back of it without voiding warranty?

If it is still under warrenty, that will be voided. Else it will depend on the model how difficult it is to open. You can always go to a professional shop and have them do it.

It is still under warranty for another year and half so I guess I'll just take it to the nearest Asus service.

That's a good plan.