Whoa,
The 5th try using zero for the AGIs and PINs from my 2018 return was rejected by the IRS in 10 minutes. I tried a 6th time after removing both of the prior year PINs and again using $0 for both AGIs.
This time it was successful!
My only worry is that although there is a bunch of Intuit mumbo-jumbo about the electronic postmark being before midnight April 15th, but you can keep trying until April 20th. I don't see any postmark that shows the first attempt in the afternoon of the 15th. The Postmark Report shows April 17.
