I agree, one of the few things I dislike about this group is when
someone asks a legitimate tech question, and some judgemental weasle
jumps on and goes on his high horse about some life issue that is only
tangentally related to issue at hand... same if for Dr.Phil.com, this
is about TOOLS and fixin stuff, not passing judgements and giving
advice. Having said all that... on to one more suggestion.

I noticed on my sister-in-law's m-wave last night there is a "+30
seconds" button. You can start it by just hitting that button. hit
it twice and it goes to 60 seconds, 3 times 90 seconds, etc. It
occurs to me that you could purchase a model with that feature, and
tape cardboard over all other buttons, leaving just that one button.
She could press it once, or twice and have sufficient control to do
her tea. The simplicity of one single button it seems would make it
very easy for her to manage.