All the cheap ones I've had that blew up were either an SMD resistor blowing out or one of the LEDs blowing out. When the LEDs blow out if you peel the board of

All the cheap ones I've had that blew up were either an SMD resistor blowing out or one of the LEDs blowing out. When the LEDs blow out if you peel the board off the heatsink you will always find a missing bit of goop under the LED that blew. Interestingly I stuck one on my bench supply (30v 2a) and I couldn't get one to blow out at all with that!