Run a jumper from the positive battery connection on the starter to the start terminal on the starter- the starter should energize & spin the engine over- if not then the starter is faulty.

If it does turn the engine over then there's a power issue to the start terminal on the starter- check to see what voltage is available to the start terminal when attempting to crank the engine using the key. I've had to install an auxiliary starter relay in many Toyotas due to a loss of voltage in the starter circuit