Go to http://tinkerunlimited.returnscenter.com
Indicate the reason for the return, the type of resolution you'd prefer and how you want to receive your return. You're highly advised to include pictures of the product, showing the issue.
The case will be approved or declined, and communicated to the customer.
If the case is approved, the customer will be provided with a return label to send the package back. You will receive an email with steps to do so.
Upon receipt, the return will be processed and communicated to the customer.
All return updates will be available on the returns center, at the link above.