No, you can't file, because the non-filers form is a short version of your TAX return, therefore doing it IS filing for 2019.
If you must file, you have to amend the tax return you did on non-filers.
You can do a regular tax form and write a note at top of form or a cover letter that you are amending the earlier efile taxes you sent in via the "non-filers" tool.
