Why is my GPU fan not spinning? AN515-42

Krisobg

Laptop: Acer Nitro 5  Model: AN515-42
Hi, I've been having trouble with my GPU for a while. It won't spin even when the CPU is at 90°C and the GPU is at 87°C so I went to a tech place and they replaced it with a new one but even now it still usually won't spin and when it does (which is rare/takes a long time to happen) it only spins at around 3k RPM while the CPU fan spins at 5769 RPM (Though it still makes a drastic change in the temperature). 
Any ideas as to what could be causing this issue and how to fix it? (I've tried to clean the fans with a cotton swab/a brush but it doesn't seem to work even if I manage to get rid of some dust)

AnhEZ28

You should bring it back to that place because they might replace it with bad quality one.