I recommend going through the repayment section again to ensure you are answering the questions correctly.
Assuming you sold your home that you previously received a first-time home buyer credit, please follow these steps to ensure the form populates correctly.
If you indicate that you stopped living in the home before Jan 1, 2023, the program will not let you make a $500 payment. You were supposed to file the form in the year you stopped using the home as your main home, to report the facts and possibly repay the balance.
When did you stop living in the home? And why?