When you void a check by mistake then there are two solutions to fix the problem:
1) Enter a wire payment. This is a dummy wire payment in the sense that no wire transfer have actually taken place. You just told Oracle that a wire transfer has taken place. This way Oracle marks that invoice as paid.
2) Other option is to enter a manual journal in Oracle General Ledger to reflect the payment accounting entry. Then create a credit memo to bring the invoice amount to zero. Pay the zero dollar invoice.
I hope that helps.
Hasan