Ignition/housing lock. Electrical or shifter mechanism?

Ok so, I have a pre owned 2000 Chevy blazer that I've always had wiring problems with. Like, when the engines off the radio stays on and drains the battery. Well I'm wondering if faulty wiring is causing my now existing headache, which is, I can't turn my key. At all.
Taken in consideration that I've been using my spare, (without an anti theft chip) for about 3 months. Which I've read, plays a part when the ignition lock cylinder starts acting up.
I had someone look at it for me and this person said I needed a new cylinder lock (its a 6 cylinder automatic tilt BTW. But I cannot turn the key into the on position to press the little button the releases it, and the steering wheel is not locked.
He then messed around with the wires under the steering column and somehow, started my car!
I thought he fixed it, until it happened again the next day. We could never get the ignition lock out. And since then, he's damaged the housing. :/


I've researched what causes similar problems and I've seen loose connectors to ECM, using a key that doesnt have the anti theft chip from manufacturer, a problem with shifter mechanism, ignition switch malfunctions and faulty gauge fuse.

How do I pinpoint the exact problem. Before he creates any more? I don't have the money for a mechanic, the last time I went to a mechanic I needed my brakes changed and it turned into routers, CV joints, axle replacement and etc. Did I need that stuff? I'll never know!
Please help!