Left our '02 parked in Drive. Now it won't start.

I would try to jump the 12v first. Then go from there.

 

A week in drive? It may have run out of gas and then drained both batteries. Try jump starting it to see if it will start. Just make dead sure you have the polarity right before you connect the jumper cables.

 

I'm puzzled. You can't take the key out of the ignition when the car is in D (Drive); it only comes out when it's in P (Park). So the car was sitting with key left in, in D gear. Was it left in "Ready" mode? In any case, you've surely fried the 12V battery, which is now dead, so you won't get any action at all. If car was left in "Ready," you may have depleted the hybrid battery as well. Charge the 12V battery and hope for the best.

 

I admit that I'm not a Gen1 expert, but it sure sounds like something's wrong with the ignition switch. Since he's nearby, maybe @ericbecky can advise.

 

If it was OFF with the key out for the week, it should still really have been OFF though, and not drained the battery.

If there's a problem with the shift interlock circuits (as it already sounds like there is), maybe that's also the explanation for not starting? It has to think it's in Park. (Not just look like it's in Park; the ECU has to be seeing the interlock signal saying it's in Park.)

But if it's really dead, no lights anywhere, I guess that's not it.

 

This is a bit off topic, but last year I got out of my 2003 Prius and had accidentally left it in Drive and Ready mode. It had kicked off and was therefore silent. I did NOT get any warning tone when leaving the car. An hour later I found that it had started up to charge the battery and had enough at idle to roll over the hill into the woods and was totaled hitting a tree - still in Ready mode and engine running when I found it. I had recently put a reconditioned battery in it and pushed the insurance co to give me a good settlement which I put into a 2002 Prius. Bought the carcass back from insurance co and had loads of spare parts, including a good battery pack.