iirc, the entire casing is "negative", so.. I dunno what you expect to see - a hole? If you punctured thru to the anode part, I'd be ducking&covering, (or holler 'GRENADE!' and loft that thing to the concrete.
If it's damaged, don't use it at all.
If you tore the heatshrink-sleeve, don't use it until you replace it. (caveat: I've used scotch-tape as a temp-fix until sleeves arrived)
Without pics, arrows and more data - this is about all the advice that applies.
EDIT: ahh, you dropped the whole mod - @JuicyLucy would be dead-on, then.