From what i understand the IRS is saying to NOT file an amend to your federal based on the new tax break they are already handling it and will be issuing the money based of your eligibility and the paperwork they already have. If your state requires you to file an amended return you will have to, however Turbo Tax Refuses to allow you to amend only the state and not the federal so it will attempt to E-file your amended return federally and it will bounce back. You will need to follow your state guidelines and maybe reach out to their tax department for instructions on how to amend just your state taxes.
Supposedly, the IRS will send you the Federal refund difference without having to amend but if you do have to amend the state, Turbo doesn't allow just the state. So like the previous poster wrote, the Fed tax will refile electronically and the IRS will reject it because they're already doing it for you. The problem is that you can print out your state amendment forms, but as part of the instructions, you're supposed to also mail in a copy of your federal return, but because its in rejected status I don't know how that will work. In CA you can't amend electronically and it has to be mailed. I don't know if all states are that way.