2023 Amended Return and IRS Letter

Hi. I received a letter from the IRS about making the payment. I did not pay all of the original amount when I filed my original return. I amended my return, my balance due was less than the original return and I paid that amount. Now the IRS wants me to pay the difference amount and interest and penalties. I'm unsure, why the IRS calculated an interest and penalty on my original return amount and required me to pay the difference. I thought the IRS would make some adjustments after processing my amended return. What should I do in this situation?

I checked my amended return online, and my amended return's status said: "Your amended return was received on April 15, 2024, and it is being processed." There is a N/A for the "adjusted and completed" steps, so does it mean the IRS denied my amended return? How can I know about the denial or acceptance of my amended return?