A lot of assumptions here. One I assume that everything worked great until you went to start the car. I would start there. Disconnect the starter (pos side) from the relay and see if you still get the current draw. Could be a failed starter or a starter who's pinon gear is binding. Failing that, try the starter relay. The starter/relay is directly connected to the batt and bypasses any fuses. A reasonable place to start, before undergoing the fun Jack pointed out.
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