Need help please!

[07denali]

Ok here is the situation. I have an 07 Denali and I bought a new shuriken 80 battery which I installed today. I have a Big 2 (yes that's 2 b/c the installer ignored me when I said to do the Big 3 and he just did it how he felt he wanted to) done and I planned to add the chassis to block ground while I installed the battery. I replaced the power alternator to fused distribution block wire, the fuse block to positive battery terminal wire, negative wire to block and added the ground to chassis. While I was taking wires out, there were two smaller wires I wasn't quite sure were for. I assumed the positive wire is probably connected to a starter and the negative wire I heard is a firewall ground. I did not replace these wires but just left them as is but and them to the battery. So after doing all this, my truck gets no power. Nothing comes on. I checked the voltage on the new battery and its 12.4v and its 12.7v on the old battery so it doesn't seem like the new battery is the issue. I'm not sure if or how to check voltage on the alternator but my thought was if it was an alternator issue, the truck would at least light up until the battery drained so I'm led to believe something in the wiring is done wrong but I can't figure out the issue. I was hoping someone could point me in the right direction before I have it towed to a mechanic since it won't start. Any help is appreciated.

[will77530]

does it make any sounds when you turn the key

[07denali]

No sounds. Completely dead. I just tried brushing the engine block in case it wasn't metal to metal but nothing.