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My vívofit 4 Does Not Power on After Battery Change
If you recently changed the batteries in your vívofit 4 and the watch will not turn on, there are a few things that you can check:
Ensure that both batteries are installed with the negative side facing the inside of the front cover.
Confirm that the blue gasket seal is fully seated in the rear case.
Inspect the battery contacts to ensure they are making a proper connection.
The vívofit 4 has several battery contact points. When installing new batteries, ensure that the battery contacts (highlighted below) are not bent down.
If the contacts are bent down, you can use a small flat head screw driver to bend them back up to approximately a 45-degree angle. The force needed to bend the contacts is about the same force to bend a paper clip.
Once bent back in place you can finish installing the front cover and install the screws.