A little more information is required Where is the leak ? Photos might help.
What is commonly called butyl "tape" is really a roll of soft putty like material used like caulking. It's just on a roll. Many, most
leaks require removing the hardware (window, roof vent etc. ) and cleaning and resealing the two mating surfaces. Shortcuts usually mean a bigger mess and the leak will continue to be a problem. Good luck and welcome to the forum.