Engine zd323 no power

Electronics went dead, replaced everything,(voltage reg, relays, fuses, ecm/controller, starter, key cylinder,) still no power, starter doesn't even kick when jumped with screwdriver so to say, batt is full charge and has 12 volts to starter lug. Any ideas?

Do you have a multi meter to measure voltages ?
Did you replace or at least check the battery ?
Did you replace the battery cables or at least remove them and clean the contacts on both leads ?

Some of the better brads use better quality power cables consisting a a very large number of strands of very fine wire, like welding cable.
Unfortunately if water gets into these cables it corrodes the copper inside the heavy outer sheath so the cables look good but actually are open circuit.