Yes of course. But I don't think you can efile it if the original was not efiled. Why did it reject?
You should not amend until the first return has fully processed and you get the first refund or your tax due payment has cleared.
How to Amend
https://ttlc.intuit.com/community/amending/help/how-to-amend-change-or-correct-a-return-you-already-...
