01 Denali XL key broke off in the ignition and after drilling it out and starting it 30 seconds later everything shuts off and battery lug melted out from battery and starter went bad.

I replaced starter but dont want it to happen again, what happened? This happened twice. Also to my 01 Silverado I had to drill it out and then when I put a new cylinder in it was fine, drove it 2 miles and everything shut off and I had to drill it out again and replace the starter.

This time just leaving key cylinder out and it's fine. I work in an autowrecking business we buy alot of gmc/Chevy full size trucks SUVs from as auctions w/o keys. So several times iv easily done this just drilled out these ignitions from 99-2006 body style and had no issues.