the underneath of the bonnet itself will give the best clue but pretty much the same way as stabbing a hole in a shaken up can of coke and firing it under there would cover it all too

either that or a sudden stop of the pump drive backing up an overflow of fluid to the pipe/reservoir which is next to the battery ?

Doesnt seem to be anything on the bonnet from what I saw.

It seemed to be all over the battery and that area. Had a look at the resevoir and the bottle doesnt seem to be split and the pipe is still attached.