Won't change channels

Trying to help mother-in-law in isolation due to COVID.

She describes that when she selects a channel, such as inputting 1 - 0 (10) that she sees it change the channel number, indicating the correct channel (ABC), but the picture never changes.

Have reset the system, had her unplug the box and plug it back in. The behavior continues.

Is she doing something wrong or is there a problem with the equipment?

Thank you.