STB won't powr-up/switch on?

Hi,
My MICO STB231 (DVB MHE05) Freeview box has lost the ability to switch on/power up after a very short power cut. Since I refuse to junk something that is probably in good order and looks like it has a has a damaged power component (ie a diode or resistor etc) but also don't know what to look for if I "open it up", can someone point me in the right direction and/or give some clues as to what to look for? Also, some advice in testing and diagnosing the problem would be good if that is possible. I'm a total novice with things electronic, but maybe this will be an incentive to learn. Thank you, Ed