page 443 of the manual:
If the Smart Entry Remote Battery is Weak
If the beeper sounds, the indicator on the ENGINE START/STOP button flashes,
and the engine won’t start.
Start the engine as follows.
1. Touch the center of the ENGINE START/
STOP button with the H logo on the smart
entry remote while the indicator on the
ENGINE START/STOP button is flashing.
The buttons on the smart entry remote
should be facing you.
u The indicator flashes for about 30
2. Depress the brake pedal (continuously
variable transmission) or clutch pedal
(manual transmission) and press the
ENGINE START/STOP button within 10
seconds after the beeper sounds and the
indicator stays on.
u If you don’t depress the pedal, the mode
will change to ACCESSORY.