I partially paid a few invoices via check and realized I have to void entire payment. Is there a way to reverse the check payments and put the tickets back to unpaid invoice?
I don't think you can "unpay" an invoice. You might actually have to go back into the ticket orders module with the constituent in question and "refund" the check there while creating a NEW invoice for the amount. The new invoice + the partially-paid invoice would equal the value of the original invoice.