Nothing. If you paper filed then you cannot also e-file.
Per the IRS:
Paper Tax Returns: All taxpayers should file electronically through their tax preparer, tax software provider or IRS Free File if possible. The IRS is not currently able to process individual paper tax returns. If you already have filed via paper but it has not yet been processed, do not file a second tax return or write to the IRS to inquire about the status of your return or your Economic Impact Payment. Paper returns will be processed once processing centers are able to reopen. This year, more than 90% of taxpayers have filed electronically.
No. That is not the case. Around January/February I reported the IRS (using Form 14039) that I am a victim of identity theft. And then I filed my paper return in march 2020. Now I got an IP PIN in June 2020.