The light that glows when it's plugged in will be a mains Neon - to show that it's plugged in and switched on.
If you attempt to bypass the broken control board you will just connect full mains AC voltage to a 12Volt DC battery - this could be dangerous and quite exciting and will result in the death of the battery and quite possibly anybody standing too close to it.
Buy a new charger...
Peccavi
November 2009