I didn’t get my second stimulus check and I qualify for it but system is stating I got my full amount and the $600 is not showing up in my refund

You should have received $1,200 for each taxpayer and $500 for each dependent under 17 years old for your fist stimulus, and $600 for each taxpayer and $600 for each dependent for the second one.

 

When you enter the correct amount of stimulus that you received in TurboTax, the program should accurately calculate the remaining stimulus due you.

The TurboTax software adds together the entries that you made for receiving stimulus check 1 and stimulus check 2.

 

Then the software computes the amount of your stimulus check amounts based upon the information that has been entered into the tax software. 

 

If you are due an additional amount, it will be issued as a Rebate Recovery Credit (RRC) on line 30 of the 2020 1040 tax return.

 

If you believe that you are due a Rebate Recovery Credit (RRC) on line 30 of the 2020 1040 tax return, then you should:

• Check the amounts entered for stimulus check 1 and stimulus check 2, and
• Make sure that you have correctly entered your dependent information.

If there is a difference, it is in one or both of these situations.

 

In TurboTax Online, you are prompted to input stimulus check 1 and stimulus check 2 information under Review down the left hand side of the screen.

 

You can also access your stimulus check choices by following these steps:

 

 Down the left side of the screen, click on Federal.

• Across the top of the screen, click on Other Tax Situations.
• At the screen Let’s keep going to wrap up.  Click on Let’s keep going.
• At the screen Let’s make sure you got the right stimulus amount, click Continue.
• At the screen Did you get a stimulus payment? you can update your stimulus check entries.

  See also this TurboTax Help.