Amazon advertises a lifespan of approximately 2,000 to 2,400 clicks for the device that we currently use for the Airnoise button. Most users typically get more than that, but occasionally a button will give up the ghost a little early. If the light on the button simply turns orange, won't come on at all when you click it, or it flashes very weakly, it's probably a goner.
You can check how many clicks your button has by going to your account settings page and selecting the Buttons tab. If it shows a "Usage" value of around 2,000 clicks, it's time to order a new button. You can do that via the green "Order a Button" link on that same page.
But can I change the battery?
The buttons were not designed by Amazon with a replaceable battery, but it is possible to change it. The plastic case of the button is welded shut, so you'll need a sharp knife to pry it open and a fresh high-power lithium AAA battery to bring it back to life. Please don't stab yourself trying to do this — an ER visit will cost a lot more than a new button.
Disclaimer: Amazon does not officially recommend or support changing the battery as cutting the case open to do so may likely damage the sensitive electronics and antenna inside. Therefore, Airnoise does not offer any guarantee that replacing the battery will revive your button, for one extra click or 1,000. tl;dr You're on your own!
If you decide to MacGyver the button and replace the battery, you'll need to do a little bit of work once you've changed the battery.
If you have an "enterprise" button with a DSN starting in "G030 PM..." then just reconnect it to your WiFi using the AWS IoT 1-Click app that you used to set it up originally.
If you have one of the original "legacy" buttons with a DSN starting in "G030 MD..." then you will need to restore the security certificates on it in addition to reconnecting it to your WiFi. Please contact us if this is the case, or if you're not sure.
Steps for restoring the security certificates on a legacy button are here.