Heated bed on Mega2560 & RAMPS 1.4 showing 358° C?

So I have this printer for awhile now (from Kickstarter) and one of the component just quit and I don't know where to start to diagnosis the problem. It's a Rigidbot Big that is running a board based on Arduino Mega2560 & RAMPS 1.4. Not sure what the problem is (short circuit?) but Cura is reading a very high number whether the heated bed wires are plugged in or not at 358° degrees C.

- I have tried replacing the wires that connect from the board to the heated bed.
- Also did a continuity test but I don't know what I am looking for. Pin 2 seems to connect to,4,6,8,10,9 and shows a reading. When I connect pin 2 to 1,3,5,7, the red led light up on the board but no reading so I don't know what all these mean...
- I tried using Pronterface but it also show really high setting.


Link to Wiki:
[rigidwiki.com]

If the heated bed plug (which in this case includes thermistor wires) is unplugged and your still reading high temperatures, then the ADC pin on the mega2560 is likely damaged.

Last thing to check, C45, make sure its not shorted.

Looks like they also did a modification on the board with the soldered on wires. Looks kinda messy. Could is be that is the ROSC pin? I see five stepper drivers, with a little bit of luck there is an option to add a second hotend. In that case you can instead use the 2nd hotend thermistor connection to read the heated bed temp. I however have never attemped to do this so I'm curious if it's an easy fix or not.

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http://www.marinusdebeer.nl/

Thanks for the suggestions. Beside the wires melting, there were no sign of any damage on both the board/headed bed. How would I test to see if it is the ADC pins that failed? Do I do a continuity test to ground on those 16 pins?