My Lexus RX350, 2007 model refused to start, the security light does not turn off

 

Most likely a defective battery. You can have the battery condition checked at most auto supply stores at no cost to you. If you have AAA roadside service they will also check the battery at no charge. The security light will blink once the key is removed, locked or unlocked. Even a defective battery will provide power to the security light, but not enough to start the vehicle.