Factory alarm help

so recently i disarmed my factory alarm i just tapped in to the green wire and grounded it, now my battery is dead and its brand new along with the alt.

was i supposed to cut the wire and ground one side or? i know that would be the only thing i,ve done recently to the car is 93 ls400 and i've read the guides i've searched for on google but none say weather or not the wire needed to be cut and whatnot so if anyone here knows would be a great help so i don't need to turn it back on cuz its spontaneous and annoying