If the robot takes instructions in human language and emulates somewhat human-like interaction then I think it would not be that hard for any generation to get used to using it. I agree it would take time before it becomes wide spread thing but not because of it being that much alien or new tech with new kind of control but rather because of price. People here compare owning robot to mobile or computer but it would be less affordable, more like car or renting real person for service. (And it would be even more expensive in the beginning) In the same time it may need as much upgrades and replacements as phones and computers... For combination of those factors I think robots ownership would not become that widespread, instead people will rent them.

The robot could actually help your grandma what the the updates...

There are other things that would have problem with people getting used to it. For example Mojo lens, smart contact lenses and other AR stuff. It is totally new user interface. But talking to a robot and telling it what to do seems like no brainer. Tho some pushback could be psychological, the interaction could be uncanny.