Syncing
If a previously synced Wii remote blinks but does not connect to your console, it may need to be re-synced. There are two ways to sync your Wii remote to a console: a standard synchronization and a one-time synchronization. The standard sync is what you should use for Wii remotes that belong to you; in this mode the synchronization data is stored within the Wii remote. The one-time sync works best for guests who bring their own Wii remote, or to change the player order of connected Wii remotes.
Standard Synchronization
Open the front flap on your Wii console and locate the red sync button; this will be in the same place where you insert an SD card. Remove the battery cover on the Wii remote that you want to sync and find the red sync button. If you want to sync multiple Wii remotes, sync them in preferred player order (i.e., the first player remote first, and so on). Press the sync button on the Wii remote first, and quickly afterwards on the console. Once the lights on the controller stop blinking it should display the player order.
One-Time Synchronization
With a one-time sync the Wii console does not store any synchronization data and, instead, temporarily overrides the standard sync data in the Wii remote. Turn on your console with a previously synced controller and open the home menu. Choose "Wii Remote Settings" and select "Reconnect." Press the "1" and "2" buttons at the same time on the Wii remote you want to sync.
Battery Levels
When you first start your Wii remote the lights will blink to give you an indication of the battery level. Four lights blinking means that your batteries are still full, and a single blinking light means that your batteries are nearly dead. You can check the status of your batteries either from the Wii home menu, or by removing the battery cover and pressing the sync button once to display via the LEDs.