My vote is either the front trim ring turns slightly and then pulls out or (less likely) there is a screw through that hole on the bottom of the light. Option C is there seems to be a notch between the trim ring and reflector, that may be a pry point to pop the trim ring off.
The four smooth bolt head that you see are probably holding the mounting plates into the reflector.
Once you get it open, unplug the bulb and a multimeter will tell you if the bulb is good (and if the generator is good).
The four smooth bolt head that you see are probably holding the mounting plates into the reflector.
Once you get it open, unplug the bulb and a multimeter will tell you if the bulb is good (and if the generator is good).