88 7mgte auto major electrical prob

[Noel]

A friend of mine just got an 88 7MGTE. Problem is the previous owner tried to boost the car with the boost cables set upin reverse polarity. the end result was all the resetable breakers (2 on the junction block on the driver side and one on the passenger side needed to be reset. Now the situation is the 7.5 Amp Ign fuse on JB-1 continues to blow. We have disconnectged the ECU and the alternator and pulled all the fuses except AM1 and the Ign fuse, which is supposwed to feed the ECU still blows when the ignition is turned on. We have also tried disconnecting the fuel relay, thestqarter relay and the O2 sensor as recomended by a Toyota Mechanic with years of experience.
In the few seconds before the Ign fuse blows the windows work. Once blown only the door chime works. I have been able to find most of the wiring diagrams and as far as I can see only the charge light and the feed for the ECU are loaded on that fuse.

Any one with some ideas would really be appreciated.