2008 Buick Lucerne new programmed PCM won't let me program my key!

I have a 2008 Buick Lucerne CXL and I just replaced the PCM. My car stalled while driving on a busy highway 5 minutes after starting the vehicle. The car wouldn't restart and so I had it towed home. It threw a P0520 code. I changed both the Oil Pressure Sensor and the Crankshaft Position Sensor and nothing happened. The car would turn over, but not start. I was told by several people that the PCM needed to be replaced so I bought a used PCM from ebay and the seller took my VIN and programmed the PCM for my vehicle. I installed it on my car today and now I cant get my key to program to the new PCM even after following the directions they sent to me to follow. When the key is turned to the ON position, the check engine light comes on and stays on while the key is in. The security light comes on and then turns back off a few seconds later. The directions mentioned that this light should stay on the whole time the key is in for the "key Program" procedure. I'm also hearing a clicking noise from somewhere in the dash while the key is in the ON position. I did get the door locks to pop and the horn to honk the very last time I tried the "key program" procedure. Currently the battery is completely dead from so many tries. I'm going to get a battery charger tomorrow to charge back up. Any help is appreciated!