RUMBA heaters-blown something, then won't stop heating up.

I have just finished building a dual extruder printer using a RUMBA.
The printer is a Rigidbot.

To help understand, HE0 is the board connector, and heater-0 is the heating resistor on the extruder.
both heater-0 and heater-1 are 24V.

I had all the axis working well, and fan0 and fan1 are also working.
Heater-0 (HE0) was working well.
When I tested heater-1 (HE1) the whole board sort of reset itself, then back on again. This happened again when I tested it again.
I then tried to start eliminating things that could have caused it so I swapped cables around. This gave the same effect, thus confirming that there must be something wrong with the heater-1??
I then crossed the cables over, so that HE0 was heating heater-1 and visa versa.-----------Big mistake.
I had a quick flash followed by some smoke.
Now when I put everything back to the original configuration heater-0 heats up without being told to, and without stopping.

Can anybody give some advice as to what initially went wrong,
and also what could be blown on the board? I think it might be one of the resistors adjacent to HE0?

What are the "12V select" pins for near the fan0 and fan1 pins?






A link to my firmware (Marlin)