Backside is metal disc with thermal paste between it and the metal mount to which it is screwed. Input is 6.75V 200mA.
What function does the PCB circuitry serve? Is it stepping down the voltage or limiting the current, or both?
Is U1 a current limiter? voltage regulator?
Is ZD1 a Zener Diode?
Here is an image from someone else: https://www.eevblog.com/forum/reviews/ikea-led-power-supply/