There is nothing for you to amend.
Follow the instructions in the CP09 notice you received or go to this IRS website for a CP09 notice - https://www.irs.gov/individuals/understanding-your-cp09-notice
As noted on the IRS website -
If I'm eligible for the credit, when will I receive my refund?
We’ll mail you a refund check in 6-8 weeks if you don’t owe tax or other debts we’re required to collect. If we deny the credit, we’ll send you a letter of explanation. If you don't hear from us after 8 weeks, you can call our toll-free line at 800-829-0922 to check the status.