Says my federal return was printed - but I need to change an item. I can't get back in and 'amend' doesn't work

To access your current or prior year online tax returns sign onto the TurboTax website with the User ID you used to create the account - https://myturbotax.intuit.com/

When you sign onto your online account and land on the Tax Home web page, scroll down and click on Add a state. 

This will take you back to the 2020 online tax return where you can make changes before filing the tax return.

Printed means you have to print it out and mail it yourself.  Did you mail yet? If not you can change it.

Then You can try to switch to efile.   Click on Add a State to let you back into your retun.

  https://ttlc.intuit.com/community/e-file/help/how-do-i-change-from-mail-to-e-file-in-turbotax-online/00/26985

Or if you want to mail a return from the Online version

https://ttlc.intuit.com/community/printing/help/how-do-i-print-and-mail-my-return-in-turbotax-online/00/26258

When you mail a tax return, you need to attach any documents showing tax withheld, such as your W-2’s or any 1099’s. Use a mailing service that will track it, such as UPS or certified mail so you will know the IRS received the return. Don’t forget state.

Important! Mail Federal and State in separate envelopes and mail each year in separate envelopes.