Starting up there is a screeching sound that is constant until I turn it off

Welcome to 2CarPros.

Is the engine starting or do you only hear the noise? If the engine isn't starting, it sounds like the starter Bendix is bad. That is the component which kicks the starter gear out to engage with the flywheel to turn the engine. It could be even a loose starter or a bad flywheel.

Can you record what is happening and upload it for me?

Here is a link the explains how the Bendix works and how the starter, in general, works:

https://www.2carpros.com/articles/how-a-starter-and-solenoid-works

If you determine it is the starter, here is a link that explains how one is replaced:

https://www.2carpros.com/articles/how-to-replace-a-starter-motor

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Let me know if the engine is actually starting. It could even be a belt issue. Additionally, let me know the engine size so I can get you specific directions for your vehicle. There are several different engines that came in this vehicle.

Take care,
Joe