The cap could have failed due to poor design, cheap manufacturing, heat stress, over voltage, water ingress or a lightning strike. It's anyone's guess, but LED bulb failures are often less catastrophic than this.
The LEDs may have failed too. Test the strips with a diode meter or low voltage DC source.
Seriously, trash the mains PSU part and keep the LED arrays as they might be usefull for some other project using a safe and proven DC supply.