Let's say you got a $2,000 refund when you first filed, but after amending you owe $500. Does that mean you need to send your $2,000 refund back, along with another payment for $500?
Luckily, the answer is no. The $500 on the amendment doesn't mean that your original $2,000 refund has been replaced with a $500 tax bill. That's because on amendments, the refund/owed amount resets to $0 and the new amount reflects the additional refund or tax owed amount from the amendment.