Toyota Repair: 98 Camry blow 100A fuse, s system, electrical problems

Question
my 98 Camry parked in Garage over 4 month and the battery was dead. I used a 200A starter and it still wouldn't start so I set the battery charger in 40A mode to charge the battery for about 5 hours. After I disconnected the charging cable, I found the head light was on even without a key. Then when I tried to start the engine with the key, no instrument lights at all. The car did crank but wouldn't start. I removed the key and disconnect the negative end wire from battery. The head light turned off and I found the 100A alternator fuse was blown. After replaced the fuse, when I tried to reconnect the negative wire to the battery, the head light came ON again and the 100A fuse was blown again.

Can you help  to find out what caused the head light to stay ON without the key or key in OFF position and why it blow out the 100A fuse?

Thanks a lot,

Mike

Answer
Electrical problems like this are too involved to deal with here, there are too may possible places for thye short to ground or another circuit may be since the 1000A fuse supplies power to almost everything else in the car's system. Since it was parked for 4 months there is a possibility that rodents chewed on some of the wires, maybe a close inspection of the wire narnesses under the hood would reveal something, the 100A fuses are not cheap so I would recommend getting a 100A circuit breaker and connecting it where the fuse goes, it will just trip and reset instead of blowing the fuse until thye short is located, with the breaker installed try disconnecting some electrical components or removing some of the other fuses one at a time and see if the fuse stops blowing, this would give you some idea where the short may be, I may be able to help once you know which circuit may be suspect.