I have the same problem as you (unit does not turn on). Today, I managed to open up to check the wiring. I have no idea if this is the correct way to do it, though.
All around the side of the cleaner (near the bottom), there are a series of tabs. You have to push them and then prise the plastic parts apart. I then found what looked like a white plastic chord running all around the cleaner. I worked it out with a screwdriver, and once it was removed it was a simple matter to open up the case.
Once open, I checked with a multimeter, and I'm pretty sure there is a fault (open circuit) in the chord winding mechanism. Unfortunately there is a note on this mechanism saying "do not open, replace as a unit", so no easy fix.
I have not yet sucessfully re-assembled the cleaner; although I have only tried once.
I am debating with myself whether it is worth getting repaired, since the cleaner is already nearly 10 years old. Perhaps the unit is getting to the age where everything will start to break down.
Would be interested to hear how you go.