What the correct pronunciation of ZENIT?

My guess is it's Z-nit, as opposed to ZEN-it.

Or is it something entirely different?

both are technically correct, depends what accent you have in Russian . Georgians like myself will say ZEN-it, people from Moscow regions will say Zin-it

So Z-nit is off-the-table, correct?

And I assume no one would say ze-NIT or zen-IT.