Transformer and 12v lighting
Depending on the style and brand of light the transformer may be mounted right at the ceiling pod itself. These may be able to be dropped threw the hole in the ceiling. I would first advise trying to find out information on the light units. Is their a brand and model number visible anywhere on the fixtures? You may be able to get info on the diagnostics and service direct from the manufacture. Yes, the transformers can crap out on 12 volt lighting. Did the lights go out in the groups the my have a remote transformer powering them in groups and it could be easier to access if located in an unfinished space of the home? I know more questions then answers, I hope I helps find yout a place to start.