Sony ecm 719 doesn't aseem to be working properly

I bought a stereo sony ecm719 off ebay.
When I connected it to my computer and recorded some music from speakers near the computer I noticed it was not good quality and sounded really strange. The computer also seems to indicate that the mic recorded in mono. I did not get a battery with the mic so have bought one and will try this to see if it changes the problem.
Should this mic without plug in power and without a battery still be able to pick up something or nothing.
I am worried cos I need the mic for a concert in 2 weeks and may not be able to get it replaced.
Any help would be appreciated.