Troubleshoot when nothing happens after removing 1st gen Nest Protect's battery tab

Here’s how:

1. Remove the two screws on the back of Nest
Protect with a small Phillips screwdriver and
take off the cover.

2. Remove the batteries in each battery tray,
make sure no pieces of battery tab remain, and
reset the batteries in the proper orientation.

3. Press down on each battery to make sure
that both ends are touching the Nest Protect
contacts.

Note: You will need to push the spring-loaded
battery so it stays out of the way to get the third
battery into each tray.

3. Once the batteries are reinstalled, reattach
the battery door by sliding it into the tabs
located on the opposite side from the
batteries and replacing the screws.