This just broke. It stopped working one day without smoke or smell.

It has been connected to a 12V lamp which it could dim. Beside being most times switched on and off by a switchable wall socket touching the lamp a short time switched the light also. Holding the lamps case made the lamp dim down, back up, down again and so on.

I'm not an electrical engineer, but I know some very basic of the parts I can find inside the device.

How would I go about trying to figure out why this thing stopped working and maybe repair it by exchanging some of its components?