I'm reopening this old thread. My old DVR died, and I got a replacement. I knew about the Last Channel Viewed setting (the dead DVR was set that way), and I set the new DVR that way (rather than FIOS News). However, the DVR still insists on showing me Channel 501 when I turn on the DVR.
I've tried explicitly setting the start-up channel to FIOS News, turned the DVR off, and turned it on again. The DVR was tuned to channel 501, as expected. Then I changed the setting to Last Channel Viewed, tuned to a different channel (not 501), turned the DVR off, then on again. As it came on, I fleetingly saw the channel I had previously tuned to, then the DVR switched to channel 501.
I have tried a full reset (reboot), but that did not change the outcome.