computer cannot find printer anymore

Hi I pluged in my printer and followed the guide and got it working. When I was testing all the axes and re calibrated the z-axis the connection died. After that I cannot find the com port on any computer and I dont know if the bord has died or what.

When I swith the printer on, one green light is shining should there be more?

Also when I looked at the underside of the printer for the first time (after the problem) the green cable from the heatbed were hanging loose. Could this have short circuited something?

If a light should be flashing or something similar, please upload a photo of it.
Is it possible to reset the arduino board or something similar?

 

I have found the problem after some reserching.

The arduino chip have been fried. probably both the arduino mega and the ramp on top of it. the ramp have a burnt mark, and the other doesnt light up when connected to pc. Doesnt feel that good if Im to leave the printer working during night if it can burn that easily.

Now what is left is to find out why and how to install a new one.