No need for going happy, it just has to make sence.
Ok, why he is to dependent on the machines. Well, maybe he doesn´t have to me so serious, indeed. Like his personality. I just want to make him looks serious at the first time, when we see him, for the effect "Watch out, we have a badass over here", and also, when the man with serious face start panicking, due to the think, which is written in the letter - there must be something really important. He could be a dump-genius, like Sheldon from BBT, or Einstein afterwards. But from the start, it could be better for him, to have a cold-brilliant-scientist face. He can stand a little bit in a shadows, and after he read that letter, we can change the light and BAM - dirty guy, with some smushy little things in his hair...
Maybe, we start to think about what is written in that letter. Why does he need a clean shirt? For who he would do all these things?
One of our idea was, that its going to be a love letter. His lost love, from the past is coming to visit him. Then we can have ending, like she is not coming, or he will split that coffee, and she is going to be a bitch, and after she see him, she will slap the door.
Or it could be his mother! And for her, he is always going to be that little weird sweet boy, playing with his toys. And everyone is cleaning up, when the mum is coming over. And what is she going to do the him, when she will see him in such a mess...I don´t know. What would your mother do?
And why he is so addicted to robots? Maybe after many years of inventing, he could just forgot, how to do all these things. Because he is much more focused on the science! Looking into eye of the God. Or something like that...
And don´t worry, I don´ t think, we would end up like ten jehož jméno se nevyslovuje. It didn´t had a story at all.