Chevrolet 2007 HH7 Owner's Manual page 100

Battery Replacement
Under normal use, the battery in your remote
keyless entry transmitter should last about
four years.
You can tell the battery is weak if the transmitter
will not work at the normal range in any location.
If you have to get close to your vehicle before
the transmitter works, it is probably time to change
the battery.
The KEY FOB BATT LOW message in the
vehicle's DIC will display if the remote keyless
entry transmitter battery is low.
Notice: When replacing the battery, use care
not to touch any of the circuitry. Static
from your body transferred to these surfaces
may damage the transmitter.
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To replace the battery in the remote keyless entry
transmitter do the following:
1. Use a flat thin object to separate the bottom
half from the top half of the transmitter.
2. Remove the battery and replace it with the
new one. Make sure the positive side of the
battery faces up. Use one three-volt, CR2032,
or equivalent, type battery.
3. Put the two halves back together. Make sure
the cover is on tightly, so water will not get in.