How can I tell if I have a bad ECU?

[akawaiilemon]

Car cranks but doesn't start, as far as I can tell the fuel pump is turning on but not sending fuel. Can't check codes, scanner can't communicate with ECU. Is it possible I just have a bad ground? I've gone through wiring more than once and I have a spare ECU. I don't want to try the spare once just in case it gets fried and I'm out two ECUs instead.