'03 Prius won't start after body work

Note: This isn't my thread. @kayodeolubowale posted this as a follow-up to another thread, rather than starting a new thread; I have posted it here as a new thread so it won't get lost. Quoting their post:

 

A Prius won't start if it thinks the shifter handle is not in Park (P). You might try stepping on the regular brake, and then working the shifter handle all the way from P to B and back a couple of times. Then, try to start it again. Or, step on the regular brake and then use two hands: with one hand, turn the ignition key to Start and hold it there, and with the other hand, push the button on the shifter handle, and wiggle the shifter handle around - maybe even try to take it out of Park. If the car suddenly starts while doing this, then the switch that senses the gear shifter position either needs adjusted or replaced. Please be careful when trying this - make sure the car is in a place with plenty of room in front of and behind the car - because the car might try to move when the engine starts.

Do you have exactly the same key now as you did before you took the car to the body shop? If the body shop installed a new door lock or trunk lock, they might have given you a brand new key. Prius keys have a small chip in the head of the key (inside that fat plastic piece) that "talks" to the immobilizer (security computer) when you try to start the car. So, even if the notches in the metal are correct and allow the ignition switch to turn, the computer will say "no" if it doesn't recognize the key, and the car will not start. If you still have one of the keys that came with the car, and it still can turn the ignition switch, you can use that key to "teach" the immobilizer about a brand new key, so either the key you have or the new key will start the car. The procedure is in the factory service manual. A good automotive locksmith will also know how to do this, probably at a cheaper price than the dealer. An independent mechanic shop (not Toyota) that works on a lot of Toyotas may also be able to help.

Did the body man do any welding on the car when working on it? If he works on modern cars (anything past the early 1980s), he should know to weld on a car without damaging the car computer(s) - basically, disconnect the 12 volt battery before welding anything, and put the welding ground cable as close as possible to the place being welded. If he did not do this, then there is a small possibility that the immobilizer computer was damaged, which would keep you from starting the car. An independent mechanic shop that works on a lot of Toyotas can tell for sure if this is the problem. A good automotive locksmith shop may also be able to find this problem.

I hope this helps!