When starting a new 2023 tax file for an LLC, turbotax business starts a clean file and does not let me open a file. What am I doing wrong?

What file do you want to open?   A 2022 file?  You have to Transfer it not open it.  When you first start a new 2023 return it should find all the 2022 files on  your computer and ask if you want to Transfer it.  Or you can browse to where it is.  You need to have the .tax2022 file on your computer.  Try again.  Start over and start a new 2023 return.  It needs to be the same kind of tax return like 1120 or 1065 etc.  Maybe you started a different kind of business return.    

When you log into TurboTax for 2023, they've added a new option where you can select Personal Taxes or Business taxes.

It's a misleading question with no definitions.

You'd select business if you need to file a Partnership Returns, Multi Member LLC etc- the 1120-S and 1065 Forms.

If you have a single member LLC (Schedule C) business you need to select Personal. 

Hope that helps