Yes, I updated my 616 tonight, from the 0300 to 0400 version, using USB, after losing my HDMI video out. Oddly enough, it had been working for quite some time, but for some reason it stopped today. Tried a couple power cycles, and then also hooked up to the 2nd monitor output, which did work. But there is no on-screen display on 2nd monitor. At least not while I could use it.
So I updated the firmware, and used the remote and the front panel to do it. One thing I noticed, I had the zipped file on the thumb drive along with the unzipped files, and I think they were in a dedicated directory on the drive. The receiver didn't seem to recognize them; it must be that they need to be in the root directory, since at first the receiver didn't give me the option to update from USB.
Once I put those unzipped files in the top/root directory, it recognized the USB update as an option from the setup menu.
It's really odd that the unit suddenly stopped with the HDMI out today. I had been watching on the remote TV earlier in the day.
At this point, if I had to do it over again, I'd probably go with Denon, given all the issues with this receiver. I do like it, nice sound, and I like the two-output HDMI capability, but who knows how long this thing will work?