You've got a very nice camera there if you get it working again. As zenrhino said, it's probably the battery contacts. Give them a thorough cleaning and see what happens.
The battery is only needed for the light meter, everything else is completely mechanical. You could still use it and guess exposure, if the meter is broken.

I'm not sure, but I think the MTL 5 already has a bridge circuit that adjusts the voltage for the metering circuit, so you don't need the banned mercury cells or special hearing aid batteries.
I had a LTL 3 (which was an earlier model than the MTL) and used a regular 1,5V LR44 cell with some aluminium foil... somewhat higher voltage, but it worked alright at least for negative films where wrong exposure doesn't matter that much. Even if it doesn't work with your camera, it won't fry the metering circuit, so try it.

Also it's Praktica, not Practika