Adobe is the only one to deal with your invalid serial number. We are not Adobe. We are Premiere Elements users trying to help other Premiere Elements users with their Premiere Elements workflows.
Click on the following link to contact Adobe via its Adobe Chat to quickly and professionally resolve the issue under the circumstances that you presented.
When the link opens, click on the statement "I still need help." to bring up the Adobe Chat pop up.
Please let us know the outcome.