A Cyberzombie is the ultimate badass opponent. If your Cyberzombie gets defeated by simply pulling some switch it would take away from the drama and excitement. In my humble opinion, if the runners don't think back to that fight and shiver in fear of the enormous personal costs it involved - even though they won - something went wrong. There shouldn't be a situation where they cheer and kill it, walking away while high-fiving.
I really like the approach that the runners need to do some research, breaking into a lab or something to gather intel about this particular Cyberzombie.
It implies that the creature is not defeatable otherwise (and it shouldn't with all the best hardware money can buy, driven by expert combat and tactical training. Keep in mind its not stupid and highly mobile. A Cyberzombie could just retreat to come back later), and it needs the help of all runners not just one, which is always funnier for the players.
Assuming the runners actually have a hacker available (should be a player), one solution might be to find a way to activate his wireless transponder (let's call it antenna).
Before that he is not reachable via wireless attempts to hack. Call it a precaution of the original maker in cases of autonomous action, to prevent this bazillion-nuyen investment to get bricked by some punk-ass hacker.
Only from a specific console at a specific location (whatever secret lab or facility you might find worthy for this endfight) his antenna can be activated.
This scenario leads to,
a) The runners need to lure the Cyberzombie to the location (which could be hard if you rule that it knows about its 'antenna dilemma') and close to the short-range transponder.
b) They need to play with it while the hacker attempts to hack the protected console, to deactivate it.
It would involve all runners to participate, create a great deal of suspense and the dramatic sacrifice option where runners really take hits to keep it where it needs to be.
And it gives you a lot of things to twitch to create the exact atmosphere you want. Too easy so far? Make something on the console break because its so old - hacker needs to repair it fast. Or let the Cyberzombie see through their trap and try to retreat - until a runner comes out of cover and taunts it. The runner is no in a duel to the death which he can only hope to win by surviving long enough. You get the idea.
Hope that helps. Would be nice if you let us know how it all played out, when it's done.