Lexus ES 300h Owner's Manual page 431

430
6-3. Do-it-yourself maintenance
Replacing the battery
Type A

1 Take out the mechanical key.
2
Remove the cover.
To prevent damage to the key, wrap the tip
of the screwdriver with tape.
3 Remove the depleted battery.
Insert a new battery with the "+" terminal
facing up.
Type B

1 Take out the mechanical key.
2
Remove the cover.