You have until 4/20/19 to fix a rejected extension.
To fix a rejected extension:
Selecting "File Extension" at the bottom of the left-hand navigation panel in TurboTax on the "My Tax Home" screen will allow you to fix your rejected extension and re-submit it to the IRS before the date of 04/20/19.
The IRS gives a grace period of five days to fix rejected extensions and returns and the original submission time stamp will be honored.
If your rejected extension is not fixed prior to 04/20/19, EZ Extension will be unavailable and your tax due payment to the IRS will then be considered late. When considered late, your payment due will be subject to late fees and any penalties and interest charged by the IRS.
A quick search online says that it should be in the email I received, but the email had no "fix" link. I cant find anything on the TurboTax website that has this either. Thank you!