hey all, i have a 1991 gmc sierra 2500, i used my truck to boost another and the helper on the other end of the cable crossed the jumper cables when he conected to the battery, it completely shut dowm my truck. it started up after that and ran. i used it to work, parked it and when i tried to start it at lunch it wouldn't start so i got a boost from a friend, it started i drove home and after lunch it wouldn't start again, i put a trickle charge on the battery over night it has an auto shut off when battery is charged, but won't start the next day. the dome light came on when i opened the door. i turned the ignition and the starter made a noise but did not turn the motor, i tried turning the ignition again nothing, i unplugged the negative terminal on the battery which is about 5 months old and tried it again in an hour, the dome light worked when i opened the door, soon as i tried the ignition key it killed all power and no start of engine, any ideas on what is killing the power? 