DO NOT file an amended tax return with the IRS. If you entered an amount but made a mistake in calculating the amount, the IRS will calculate the correct amount of the Recovery Rebate Credit, make the correction to your tax return and continue processing your return. If a correction is needed, there may be a slight delay in processing your return and the IRS will send you a notice explaining any change made.
To check the status of your refund from your original return, check Where's My Refund?