Get your taxes done using TurboTax

When you used the non-filers form on the IRS web site, did you finish it and get an email that it was accepted? 

Because if it was accepted, that means you efiled through that.

You can't efile again.

You can file an amended return.

Also, you can send in a paper return and make a notation at the top that it is an amendment to an efile you did through that portal.