MK133 blown due to reversed polarity

I appear to have blown something on the MK133 quiz table when I accidentally tried to connect a battery the wrong way round when the switch was in the On position - the board is now completely dead.

I am assuming I have blown one of the components close to where the power wires join the board - I suspect it’s one of the diodes or transistors. Before I try unsoldering the components one by one to test them, can anyone suggest which one might have blown?

It was D9 - attached to the +ve power line - I replaced it and all is well again

The circuit is protected against polarity inversion.
I think only D9 must be replaced (you can use a standard 1N400x diode).