Sounds like we should try to get the start circuit working. We will need a way to verify voltage. I recommend getting a 12V lamp with alligator clips. Verify it works with the battery.
With the battery connected, connect the lamp between ground and the input terminal of the solenoid. If the light burns, this verifies that there is voltage on the input of the solenoid. This is good. If no light, we have figure out why.
Next find the large wire coming from the starter to the solenoid post. Connect the light to ground and this terminal. The light should NOT be on. Now engage the solenoid (loud click) with the key (or however you do it). The light should come on. The starter should turn. If there is NO LIGHT, there is a problem with the solenoid. If there IS A LIGHT and no starter turning, there may be a starter problem.
Let us know how this test comes out.