no crank no communicaton with scanner

it sounds like you're using Snap-on equipment. I think they have a help line you could call. They'll tell you if you have the right key, etc.

Check ALL of your fuses. The no communication can be a cig lighter fuse that is burnt out. You may also have to clear a security code once you replace the battery. Also make sure that the cables are connected to the correct sockets, i.e red to positive and black to negative, I have seen more than 1 Tech get the incorrect battery and install it with out making SURE that the sockets were on the right sides and then do damage to a vehicle. Hope that these suggestions give you some help. Key #20 is the generic OBD-II and GM key so it should work. ( I use the Snap-On Modus as well )