Here is an inconsistency regarding serial numbers.
In an earlier communication, I was asked to input the serial number as found on the bottom of the malfunctioning Roku unit.
That serial number was 7G2697945131.
That same number is on the label on the box the unit came in when we bought it.
In our Roku account that serial number does not appear.
We have two Roku devices, and two Roku devices show up in our account as the following serial numbers:
In the activation process this morning, I named the device "Roku_upstairs".
That device shows up in our Roku account with serial number YU007T945131
I don't know whether this information is significant in regard to the problem, but I'm supplying it anyway in the event that it might be.