If you start the year with -$100 in assets and end it with $0, that's $100 net income.

It doesn't matter much if you add to a negative debit or a positive bank account. If AMD was investing into some non-formal asset (brand awareness, R&D, etc), the numbers would change, but that's not the GP's scenario.

The only way paying down debts can affect income is by reducing interest expense, which would make income go up. If a debt was written off by a lender and would no longer be collected, that would affect income (although that's not "paying down") and would also increase income.