Geeetech

I think I had the printer powered on, providing +12v to gt2560. I'll see if I can make a better guide

Thanks for the info guys, i successfully managed to get this board back to life using an arduino 2560 as an isp. can be done with other arduinos

How i fecked it up.
i chose "export compiled binary" method from arduino and updated the printers firmware via repetier server. it worked the first time ...