your ramps is faulty, or you have a short, or your pololus are in backwards, or your enstops are wired across + and - or your fets are dead, or... and the list goes on...
Im guessing dead pololus or pololus in backwards... general diagnosis follows
NB always turn off and unplug power before making any changes.
1) remove ramps, does computer still talk to the mega?
no. you have killed the mega
2) yes, remove all modules, endstop cables, everything removable from the ramps and plug it into to mega. Can you still talk to the mega?
No, you have a short on your bare ramps, you need to find and fix this. (or replace ramps)
3) yes, slowly add thing back to your ramps, one at a time. I suggest thermistors, then endstops, then pololus
You now either have a full working board, or have identified what is killing it.
Edited 3 time(s). Last edit at 03/25/2014 03:26AM by Dust.