Printhead heats up as soon as power is turned on.

Hi!

I'm assembling a Kossel XL, using an Arduino Mega, a RAMPS 1.4 Board, and Marlin.
connecting the Arduino to the computer is fine, Display shows normal temepratures around 37°C
But as soon as I power up the main power supply, the temperature on the display starts rising, reaching 300°C and a MAXTEMP Error after ~3min. It keeps rising afterwards, until I unplug the power.
Is this a Marlin Issue, and if it is, does any of you guys know what might cause it? If I missed some information, please ask, I'm just new to the Topic.
best regards,
Arved

PS: because I'm not sure where the problem lies, I also posted this in the RAMPS forum.

Edited 1 time(s). Last edit at 03/17/2016 10:53AM by Arved.

As long as you have the motherboard type set to a ramps board this is a hardware fault. probably a dead mosfet on d10
Or could be as simple as not having the ramps on the mega firmly.