A USB flash drive with 50 MB of free storage. The USB drive should use the FAT32 format.
Using a Windows PC or Mac, download the USB update package from this link here. Open up the zip archive (your browser should automatically do this upon download completion), and copy the "phorus" folder exactly as it is to the top level of your USB flash drive.
USB Flash Drive Play-Fi Module Update
Unplug the Play-Fi product from power. If product is battery powered, hold down power button until it is powered completely off (no lights on).
Insert the USB flash drive into the back of the unpowered Play-Fi product.
Plug the Play-Fi product back into power, which should make the product light up (some also make a startup tone).
After a short period of time you should hear another tone from the speaker and the power light should blink: this indicates the process has started.
After about 3-5 minutes or so--and several interspersed tones--eventually the product will make a tone every 5 seconds. This means the process is done.
Unplug the Play-Fi product from power. Make sure product is powered completely off.
Remove the USB drive.
Plug the Play-Fi product back into power, and it will return to normal operation.