Mamiya M645J not fire

I just bought a M645J on ebay, but now seems that comes defective, although is in a very very good looks. What happens in is:
A followed the Manual, setting to MULTI position, move the rotate the knob until it stop, but when press the shutter nothing happens, it goes to the end so light like a broke and nothing happens. Can anyone give some help. I didn't buy the lens and finder yet. and not sure if it should fire without them.
Thanks.

Check the battery by pressing the battery check buttom, which should light the BC light by the shutter speed knob. The shutter won't release without power. You should always use a 6V Energize 544 silver oxide battery.