This might be dumb but I have this old laptop motherboard (not so old, its a core 2 duo) and I see that this mosfet might be dead.
The only truly dumb question is the question that isn't asked.
How do you know it's that mosfet causing the problem?
Also, im not entirely sure it is dead because I tested it by connecting the positive of multimeter to the sink and the negative to the gate. Then I connected neg. to drain and back to sink and the diode test didn't show anything. However, on the other mosfets on the board it gave a reading on the multimeter. Am I doing the test wrong or is the mosfet really dead?
It doesn't mean much without knowing what else is connected to it. The only way to be sure is to remove it from the PCB and test it alone.