By the way, I have discovered that there are two ways of unplugging the box and when one way did not work on a problem for me, the other way did, so try both.
One way is unplug the box from the electrical outlet and wait 10 seconds and plug it back in.
The other way which works to unfreeze is to unplug the box connector from the box itself, wait, then replug the box connector.
Basically we are actually walking about both ends of the power supply..the plug..and the connector.
I just remember that one time when frozen, first I tried the outlet unplug but it did nothing and then I tried the connector unplug and it worked.
Hope it works for you!
Original Roku 1, called N1000,bought 2008 (2014 still works perfectly)
2014 new owner of Roku 3500 (HDMI) streaming stick