If your return rejected it was never filed. You don't amend. You just fix it and file it as the original return. Is it for 2022 or this year 2023?
For 2022 You will need to switch to the Desktop program to fix it.
How to finish a prior year online return
https://ttlc.intuit.com/community/prior-year-return/help/how-do-i-finish-a-prior-year-return-that-i-...
You will first need to download the tax data file from Online. It will end in .tax2022, .tax2021, .tax2020. You can download the tax file for free. Then you need to install the Desktop program.
After you get the program installed the first thing to do before you open your tax return .tax file is to update the program and install any state programs you had. Then open your file. So you first might need to start a fake return to be able to download the state program (go to FILE - NEW).
