Hardware tokens should last up to seven years or longer, as their shelf life depends on how they are used, stored, and temperature.
Hardware tokens that produce an Err message means that it will need to be replaced. Some of the symptoms of a token with a low or dying battery are receiving an Err message or distorted numbers.
Your token may need to be synced if you receive the message "Incorrect passcode. Please try again" after correctly using a passcode from your token. You can attempt to log in three times in a row, with a new code each time, to re-sync your token to the Duo servers. If after the third attempt, it still fails, contact the IT Service Desk.
If your Duo token is falling out of sync, it may be due to the button being pressed too many times without the generated codes being used. If a token is stored in a bag, it may cause the button to accidentally be pressed many times.