BBC camaro will not start

[mtm87tx]

Team,

Can you please help me trouble shoot my car it is not starting:

• When you turn the ignition one click everything lights up fine, shows voltage, radio/ac work
• When you turn the key to start it makes one click which sounds like the starter solenoid and then voltage drops to 0
• The starter is new
• The battery is new
• If i leave battery cables on it from the charger and wait about an hour the car will start. It will only do this once

Any thoughts? I have checked the visible wires, cleaned the terminals, etc