Sounds a bit like your ramps fuse has been triggered, so you only have 5v for the logic but no 12v for motors or heaters. In server go to console and enable ack and send e.g. M119 to see if communication is working. Then enable extruder and measure boltage at output within 10 seconds (before decouple test disables it anyway). If you get normal communication but no power it is a good chance it is the fuse on the ramps, also this should be a polyfuse and reset after a while. At least on my ramps board.
