1999 monte carlo suddenly wont turn over?

i have a 1999 monte carlo and have never had a problem with it. today i got my new car subwoofer amp in the mail so i decided to go and hook it up. i got all the wires run and the negative wire grouded out and everything. the last part was the positive wire. i went to undo the bolt which is actually on the fuse panel/box but it was rusty and wouldent come loose so i figured i run down to walmart and grab some wd40 but when i went to start the car nothing happened. all of the lights come on and all accesories work but no turning over at all. the starter motor does not make any sound at all. the only noise to be heard is a click in the fuse box and a louder click towards the rear of the engine after i let go of the key. i kept trying and after 30 tries it finnaly started. i let it run for a few minutes, shut it off and tried again and once again wont turn over. so far i have removed battery terminals and done a quick cleaning nothing crazy. and no difference so far. also one thing i find weird is that behind the bottom dash panel is a small led that im pretty shure ws installed by the previos owner. it has a black and red wire and a resistor and the led is flashing. i have no idea what this is. also the security light has been on since i have had the car and i have a spare key with no chip that works so i think the passcode system has aready been bypassed. before i take the car the garage i need some feedback just in case its anything i can do. as said before i have never ever had a problem with the car starting before.