I think you need to spend some time actually doing some of these things that you feel that you want to pursue before committing to a university degree in order to pursue them.

A lot of people mistake the idea of being something as something they like versus the process involved in being that thing. What I mean by this is, you might find you like the idea of being an ME/EE, but once it gets down to the day-to-day work in learning and being that, you may find you actually hate it.

So, start learning the basics on your own. Do a project, then re-evaluate and see if going to university would be the right choice.

As for going back to school for computer science: I would only say to do that if you plan to go straight into a graduate program. Undergrad computer science is not worth it if you already are in industry. If you feel like you're missing something, there are many books and resources that are better and significantly more interesting to work out of than what an undergrad program will offer you.