05 Pontiac grand prix. It won't start. It will and the next time it won't

Hi, I lost my key for a few months.  The car was in anti theft mode for some time.  In the meantime... there was a relearn done with no key,  my whole dash was torn apart and someone tore the anti theft ring off my ignition. I got to the ignition finally out. So the anti theft ring could be re soldered to the circuit board. Then put back together.  Also at one point my friend tried to get it started while in anti theft mode. He took the panel off the driver's door and acted like he had unlocked it with a key.  The message on the screen didn't have the disabled message and he spliced into the starter wire to hot wire it. We stopped at that point and now I have the key back.  Also it had been towed a couple times and one time being around forty miles in neutral. The starter will not work by turning the key any more but I have had it started a few times.  Now it isn't starting again.  Last night it flashed a message saying"reduced engine power" I drove it today to where I'm sitting now and it won't start again.  Do you know what is causing this?