You need to remove the hazard push button from the unit, gently pry behing this button on the short side, you will see what I mean, you need to pry on both short sides to undo the catch that it has.
Than the next step is to remove the housing, again prying gently, the housing is made of quite thin plastic, and slide this off the unit.
Surprise, IC etc. etc. fansy stuff. But you will see three capacitors, two small ones and one larger one.