Fans stopped spinning on my Asus vivobook 16 pro

last month the fans on my asus vivobook 16 stopped spinning. i didnt know what was wrong since they werent dirty, so i sent it to repair through the warranty. they replaced the fans and sent it back but the problem was still there. i also checked in the bios to see if there was a thermal override but the bios on this thing kinda sucks. so its not a problem with dirt or the fans, what else could it be?