I also noticed the strange cable of power adapter. The only simple thing you can try before sending it back (and if you didn't flash a wrong image to your box), is to find a perfectly equivalent power adapter (mine reports an OUTPUT of 12V, 5.0A, positive inside, I tell you because I'm not convinced yours is original). This try hoping it's just your power adapter that got damaged.
And, as Mick already asked, what happened before your STB started having this problem? You had just used it, switched off and then it didn't start the next time? Or you tried to flash something? Or some lightning occurred in your place?
Because, if you had (for instance) tried to flash something, this is a completely different matter.