broken heatbed (output)

Hello,

Today I was printing when suddenly my printer stopped and my lcd screen went blank. I knew something was wrong and when I touched the processor on the board it was extremely hot.
I started troubleshooting (after a few minutes to cooldown the processor) by disconnecting everything from the board and plugging everything back in, one by one.

It appeared there was a problem with the heatbed, when I connected the wires the lcd went blank again.
Using a multimeter, I found out the heatbed output was still 0V after turning it on using repetier host. And the multimeter also gives me a heatbed resistance value of 0.003 (meter put on 2k Ohm).

I have a Sunhokey Prusa i3 with a MKS gen-2Z v1.1 controller board.

Is my mosfet blown? And if so, why?

Put ohm meter on a lower range. 2k ohm range will not indicate headbed ohms. Is the ohm reading with the heatbed attached to the board or not? If not attached reading should be 1.5 to 2.5 ohms or so. Disconnect from board and measure resistance of heatbed output on board. This should tell you where the problem is.
Too much heat will blow the mosfet. They should have good heatsinks but don't.

Edited 1 time(s). Last edit at 07/25/2015 10:33AM by Putzer.

With ohm meter on 200 it gives me a value of 2.8 Ohm. The heatbed output is working now, it was simply disabled because the temperature sensor was already disconnected.

So I measured the resistance between the wires of the temperature sensor and the heatbed and they were shorted. Then I saw they were melted together.
I pulled them apart and fixed the isolation with some shrink tube.

I'm happy I was present at the moment it happend so I could pull the plug before it fried my board.