Borgs get stunned by batons and tasers.

[Weavel]

Borgs are wired electronicly, a taser or baton sends a large electronic charge into the body

therefore a borg is stunned as it's circuits are overloaded

What you want is for borg to become even more of an invincible death machine; unless you actually have a baton or a flash, a borg is essentially invincible