Common problem I find is GU10 downlights not working. 90% of the time its the chocky block connecting them to the output wires of the transformer - it basically melts.
These always seem to be inside a plastic box attached to a metal upright that leaves the box directly over the lamp so the heat can get to it more easily :-)
Seems a much better idea to keep the chocky well away from the heat of the lamp. The plastic box they are in doesn't seem to offer any protection to the chocky.
Is there a reason for this design?