It sounds as if your ignition switch might be broken! This may be due to wear but can also be caused by poor contact in the starter solenoid. Poor contact in the solenoid causes most of the current to the starter to go through the ignition switch causing the latter to fuse together. Before you try to hotwire, try running just the starter. Make a cable with a 30 - 40A fuse and connect to the solenoid control connection. Connect the other end of the cable to the battery. If the starter works without the fuse blowing the starter motor is probable OK. If the fuse blows, the starter must be addressed.
Check the ignition switch by hotwireing. If needed, replace the ignition switch.