Has your original return been accepted? You should wait until it's fully processed and you got the first refund.
How to amend an Online return
https://ttlc.intuit.com/community/amending/help/how-do-i-amend-my-turbotax-online-return/00/27577
Another way to amend is from inside your return. Open your return, you might have to select Add A State to get back into your return.
Then go to........
Federal Taxes or Personal (for H&B/Self Employed version)
Other Tax Situations
Do not try to amend your return until the original return has been fully processed---or it will create confusion and delays.
How do I amend my 2019 TurboTax Online return?
A 1040X cannot be e-filed. It must be printed and mailed. It will take about 4 months for the IRS to process an amended return. It is a good idea to use a mailing service that will track it, like UPS or certified mail, so you will know it was received.
Wait about 3 weeks from mailing and you can check the status of your amended return:
https://www.irs.gov/Filing/Individuals/Amended-Returns-(Form-1040-X)/Wheres-My-Amended-Return-1
https://ttlc.intuit.com/questions/1908543-do-i-need-to-amend