How does a RCBO trip from a vapourised PCB trace?
A dead short could easily cause tens to hundreds of amps to flow, which would trip the breaker pretty darn quickly, probably much faster than the unknown &quot;fuse&quot; in the the power strip. Such a current spike could also in theory cause induced currents on the earth line and trip the RCD portion of the breaker.
Given the breaker wouldn't switch back on until you switched off the offending socket, there was most likely there was a dead short from live to neutral on the switched side which allowed such a high current flow.
My advice would be to return the power strip to where you bought it from, or simply dispose of it (preferably via your municipal electronics waste stream or equivalent). I would not trust such a device to not cause more problems even if it seems to be working now.