Starter turning as soon as battery connected - GS 300 Lexus Cars & Trucks

Bad starter selonoid

Hi,
There are two sources I can think of that would cause the symptoms you are describing. So if I understand correctly it works out to the following. Here goes.
A The starter solenoid mounted to the side of the starter (or possibly mounted separately inside the engine compartment), is fused (stuck) into the "starter engaged" mode. The only way to stop this, is to literally disconnect the battery.
Note: If the starter solenoid is mounted separately from the starter motor, then it can be replaced separately and inexpensively.
If the starter solenoid is mounted onto the starter motor, which accounts for most vehicles, then the "starter motor/solenoid" combination should be replaced. Or it could be the ignition key as in B below.
B The starter key switch failed in such manner as that the "on" position and the "crank" positions are fused together. So, instead of the car interior instruments going into operation before you start the engine. It just goes into the engine start mode and doesn't shut off. Not good!
I WOULD NOT DRIVE THE CAR UNDER ANY CIRCUMSTANCE. YOU CAN CAUSE DAMAGE TO THE INTERNAL PARTS OF THE ENGINE REQUIRING MUCH MORE EXPENSIVE REPAIRS.
I would move the car without attempting to start it into a position where emergency work can be done safely, if you are going to do the work yourself. Otherwise I would have the car towed to a trusted mechanic.
I Hope this helps. If you have questions, please let me know through this website.
Good Luck,
Mark