A few questions to help us understand your background/history with this PODxt:
1. Did you purchase the unit new from one of our Authorized Dealers (Guitar Center, Sam Ash, Sweetwater, Musician's Friend, AMS, etc.)? We don't sell units directly to our customers, so if you ultimately decide that you need a refund/money back, you'll need to contact the vendor who sold (took your money) the unit to you.
We sell to our Dealers and they do individual sales to the public. We can't help you out if you bought this PODxt used (on Craigslist/eBay). That will be between you and the seller.
2. Typically on PODxt units that have pre-USB Firmware 1.12 software present, you'll need to use something like the M-Audio MIDISport UNO Interface as a means to update the USB Firmware via MIDI In/Out cables.
This can be tricky at times because it requires the introduction of other wildcard/variables:
A. The USB driver for your MIDI-to-USB Interface needs to be fully supported on your Mac's OSX. Typically the manufacturer should have info regarding these facts, along with USB driver downloads. You should always try to have the latest USB drivers installed from the manufacturer's website. Discs may contain older/out-of-date drivers that prevent the full ability to pass data through the interface.
B. With Mac computers, USB ports vary in terms of bandwidth/performance. You'll need to try every single possible direct USB port on your Mac before anything else.
C. USB Hubs are commonly used by Mac users, since many Mac machines don't have a vast number of direct ports. Hubs allow users to plug into 1 USB port and then split this into multiple new USB ports. Unfortunately, trying to push a firmware update through Hubs are not support, because USB Hubs limit the bandwidth when other devices are sharing the same original direct port. Please don't connect through a Hub, if you didn't know this.
3. If none of the above suggestions work, there's a chance that your unit has a hardware issue internally that is preventing updating of firmware via it's MIDI ports.
If you purchased a new PODxt from a dealer, you will most definitely have a sales receipt in your possession. Our manufacturer's New Product Service Warranty period is 1 year from the date of purchase on the receipt. Our Authorized Service Centers are the places that perform Warranty Repairs: http://line6.com/support/serviceCenters/
4. Ultimately if you like, we can return/refund your License Key purchase since it's never been installed and you're within 30 Days of purchase. Just let us know if this is what you'd like us to do.