The updater that I could find directly via iRiver support did not work, but based on one of the other tips, I googled for the Version 126.96.36.199 updater ([MTP] iriver Firmware Updater for MTP devices).
I recommend that you try the "normal" updater from the website (maybe yours is not an MTP version), and if that can't recognize your player, try the updater from the link above.
Note: The updater seemed to hang at 50% for over 5 minutes... I gave up and unplugged it. Then it asked me if I wanted to upgrade the firmware. "OK," I said. It took a few minutes. The screen went blank. I put in a fresh battery. Turned it on. It works. I was able to use Media player 11 to synch some songs to it.
BTW: It did blow away all the songs on the device, even though I chose "update" instead of "recover".