Homebrew PCBs

my camera flash circuit burned out while i was trying to check 
something there. i tried soldering something over there and suddenly 
i heard a small blast and a spark was where i was soldering. now, if 
i turn on the circuit it gets very hot (i think the transistor is 
the heat source). how do i check whether it is the transformer, the 
transistor or the capacitor that burned out? how can i check 
everyone of these components to see if they are ok?

thanks a lot, mumin.