First ensure that all the wiring is good leading from the battery to the ebox, and the ebox to the starter. Check the ground wires as well.
At the E-box expose both of the power leads from the battery, and to the starter. Take a screwdriver and cross these leads for a second. If it starts turning over then wiring and starter is good.
Time to find the fault.
I would start with checking the starter button. They sometimes corrode and don't make contact. Check with an ohm meter for continuity when the switch is pressed in. It is an easy fix if this is the problem. They are fully serviceable, open it up, clean the contacts with some sandpaper, lightly coat with an electrical contact grease or never seize, and put it all back together. 1/2 hr at the most.
If this isn't the problem then it has to be the starter relay. Again test with an ohm meter. You should be able to find the proper values online.
