Toyota 2012 Yaris Hatchback Owner's Manual page 250

Type B
4-3. Do-it-yourself maintenance
Remove the cover.
To prevent damage to the key,
cover the tip of the screwdriver
with a tape.
To prevent the buttons from
being disassembled, face the
button surface downward.
Remove the module.
Open the case cover and
remove the depleted battery.
Insert a new battery with the
"+" terminal facing up.
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