Audio Systems: Installing Headunit, bench test, toyota corolla

Question
I'm installing a headunit into a Toyota Corolla 1989 (unsure of the date). I have fair knowledge of installing headunits but this one has really got me. I first hooked up all the speaker wires and then hooked up the ground and live wires(stock wires have different colors than what they have now) but when I had everything connected and I turned the car on, the headunit turned on, just so it could turn off. so I took the live wires off and messed around with them, but nothing seemed to work and when I didn't have the ground or live wires connected (only the speaker wires) it did the same thing, it came on and said "Have a nice day" and shut off. How is that possible? so what I did next was disconnect the speaker wires and connected the ground and live wires but then the headunit wouldn't turn on at all. Would you have an explanation for this and how to fix it?
I still have my friends dash apart so any response would be appreciated.
Thanks

Answer
You must first verify the head unit is working.

You may have to pull it out and bench test it; which I recommend because you may have caused some damages by powering it up incorrectly.

Then, you must either purchase a wiring harness to fit your car and the new head unit OR trace out the wiring (speaker pairs and 12v hot lines) and label them and match them directly with the wiring diagram from the head unit - with no mistakes or you are in trouble again.

You can find a wiring harness for this car at www.installer.com or you can check the wiring diagram at installdr.com that will help, also.

Hope you get it working!
Cleggsan