Toyota PRIUS Manual page 618

5-2. Steps to take in an emergency
 Stopping the hybrid system
Set the parking brake, shift the shift position to P and press the "POWER"
switch as you normally do when stopping the hybrid system.
 Replacing the key battery
As the above procedure is a temporary measure, it is recommended that the
electronic key battery be replaced immediately when the battery is depleted.
(P. 518)
 Changing "POWER" switch modes
Within 10 seconds of the buzzer sounding, release the brake pedal and
press the "POWER" switch.
The hybrid system does not start and modes will be changed each time the
switch is pressed. (P. 279)
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