If you find that that there is no power LED or hearbeat LED on your Beagle Bone Green(BBG). STOP!
Don't be so quick to assume that it has died!
Do some trouble shooting procedures first:
1. Disconnect the ethernet cable from Acorn
2. If you have removable headers (Acorn Hardware Revision 3) unplug ALL but the power connector. If something is wired wrong it could be "dragging" down the BBG" so and easy test is to go back no connections but power.
3. Power up Acorn and see if the power led comes on and heartbeat returns.
4. If it DOES, then power it down and plug the Ethernet cable back into BBG and retest. If heartbeat is present, try and start CNC12 to see if it comes up (communication established)
If heartbeat DOES NOT come up with everything disconnected from Acorn, but the power led on Acorn does, then proceed to the debricking procedure.
If your BBG is damage by inncorect voltage applied to it, then you may order a Beagle Bone Green from a supplier of your choice, and then perform the debricking procedure to load the Centroid firmware onto the new Beaglebone.
If you have an older Acorn hardware revision, take a picture of which terminal your wires go, mark the wires and disconnect them follow the procedure outlined above.
If the Acorn heartbeat comes on and then goes off as the PC boots, disconnecting the ethernet cable may help diagnose this.
Lastly, if no heartbeat, pull BBG off the Acorn mainboard and power it up via the mini USB port on BBG as if you were going to debrick it. Does it boot up and heartbeat LED come back? If so, could be an issue with the Acorn board.
Just don't be so quick to assume BBG has died without doing basic test procedures first. Marty says..." I have been through many many Acorn builds and haven't had one BBG go bad on me yet. But I have had the heartbeat not come on, and found it was something OTHER than BBG, " so be sure to trouble shoot before debricking, Here is a link to a related thread on the Forum.
Acorn BBG debricker zip file download link.