Filed non-filer, how to fix it

I mistakenly filed non-filer form when i was checking for stimulus package thing as i thought we need to do for if haven't filed 2019 tax return. Then i right away saw the criteria and next day e-file my return but it got rejected.

 

I filed paper base but forgot to sign it . It was my bad and was in rush.Now can i send them paper 1040 with signed and put cover letter?