help 86 mustang no power period

[Riot86]

im trying to help my brother fix his screw up he switched out his starter solenoid and after doing so he started it to make sure he did it right. and it started just find but when he turn the key off the motor kept running until he unpluged the batt. then when he went to pug the batt. back in . it started it cranking again this time with no key. so he thought he hooked up the starter solenoid backwards and flip the wires around and now their is no power to nothing and then back and nothing still what happen here

[rhandwor]

Their is a fuseable link for the ignition switch blk 16 ga. The links are down by the starter. If he goes to a scrapyard to get another one. Look at the small wires at the solenoid. Make a diagram always do this when doing something different. Also look at the big wires.
Clutch safety switch above clutch pedal. Neutral safety switch on side of transmission. Ignition switch on steering column near where it bolts to dash.
Starter relay red to relay blk to starter motor. Red/lt blu to small connector. Use a test light and check for power when trying to start. It should shut off with the key. Clutch pedal or transmission not in park or neutral should also shut off power.
You can also make a fuseable link use two sizes of smaller wire. I think it should be 16 GA wire but double check. Check the wht/pnk wire from ignition switch. Then check RED/LY BLU wire to solenoid for power.