I hope everything works out for you! I know your pain of a lost pet in a car. Don't start it, if it's a newer model he should have no way to get to the engine bay, older model only way he can get out is small holes where wires run through the fire wall, if you lift your hood and look at the wall behind the engine you should see where wires rum through at multiple holes, plug those holes with something like rags to keep him from running into the engine bay and you can trap him inside the dash enabling you to get him without a chance of escape, check wires since they will run warm, metal parts usually stay cool so less likely for him to be cringed to one.