Move ECG is waterproof, and as such, we strongly advise that you take it to your local jeweler or watchmaker and request that the battery be replaced. The replacement of the battery and the reassembly by a professional will ensure the watch will remain waterproof after the battery change.
Important: To replace the battery of your watch, make sure that the + is placed in the top part of the watch, and the - in the lower part of your watch (the part in contact with your wrist). If the watch does not turn on after the battery replacement, please check the orientation of the battery to ensure that it is not the issue here.
Note: For optimal use of your Withings watch, we recommend replacing the original battery with a non-rechargeable CR2430 coin cell from Toshiba, Maxell or Omnergy.