My best advice would be to see if Mercedes has a key fob with a dedicated remote start button. Many of these paywalled systems still work fine with a physical key, it’s just the app that requires extra payment.

Have you checked your owner’s manual to see if there are instructions or something?

Heat it anyway, that should break it loose with or without locktite

If you have electric power steering you may have a sticking relay, sending power even though the car is off.

Make sure your wiring is taped up good so it doesn’t short on the engine.

Otherwise send it 🤘

This sounds like incompetence from the tow guy, there are ways to put it in neutral.

If the tires were still locked up (or one turning backward) while it went up and you didn’t hear a big snap you should be fine.

From what I’ve heard you can put a carburetor and distributor on a 5.7 Hemi with some work.

Sounds like a power steering fluid leak. Dump some in the reservoir and see if it drips, then start the car and see if it drips.