truck will not start.when I plugged in computer,no link found. on 2003 Mazda B3000

Dash indicator light dosen't come on.When turned to accessory nothing,no radio.Headlites do come on.Already replaced ignition switch.No help.Any ideas

1 answer 2 comments
ck ecm fuse then test pwr to ecm to start with
should have mentioned, I already changed both fuses.Not sure how to check for power to PCM.Fryed one in a PT cruiser once.
Was getting ready too call tow truck.Notice 50 amp relay blown (starter/ingnition).Thinking starter might be locked up.Anyone ever have this happen to them.