The problem with jobs in power electronics, like others here have said, is that you need experience to be good at it (acquired intuitions and a good design toolbox). If you are good, there are all kinds of jobs out there. It's just no one wants to train anyone. That's an investment that doesn't usually pay off for the company (since job hopping is what people do once they get the experience).
Sounds like you need to make some life decisions.
In my opinion, if you have an opportunity for a stable job with good pay and reasonable stress levels that doesn't drive you absolutely crazy, then take it! That's a win. I wouldn't pass that up for something that you think you maybe might enjoy more but don't really know anything about now. If you are young, you have nothing but time to sort that stuff out. Who knows, you may HATE being an actual working engineer of any kind and go into marketing or something.
While you are working your average job, go off on your own and learn as much as you can. Talk to your coworkers and see if any of them want to start a side project (or side business) making something fun. Keep gaining understanding, and if at some point a better more fulfilling job comes along and you have learned enough, take the other job.
Not to crap on all your youthful dreams, but if you really follow a typical engineer's career path it goes something like this:
1) Graduate and work your ass off for a number of years. Primary focus is on the job, usually neglecting other parts of life. Put in WAY more work than they are actually paying you for.
2) Burn out a little, slow down, and get a significant other. Appreciate spending time away from work a bit more than sleeping on the office couch.
3) Have a kid (or two), which takes priority in life (and all of your energy you used to use to work on stuff), and coast in your career.