Pysifr

My Moderately expensive 36 LCD ceiling light has died - with a "pop" as it was switched on. The light is no longer made but on contacting the manufacturer and explaining that it went "pop" after a couple of years instead of the 20+ advertised, they sent me their last two 36 LCD plates. When I took the light to pieces, I discovered that there is no DC power from the LCD driver. In my setup there is a small white box (about 2.5 cm long by 2 cm square) in the 240 volt mains supply to the driver, with no indication what it does. My issue is that the drivers I see for sale are just that "drivers" - even the identical driver has no such box attached. What is this small electronic device doing, and how can I test to see if this is the problem? I have attached photos. Many thanks Ian