If your SkyBell is blinking red and blue that means it is not getting enough power to fully power on. There are various causes for a power issue, here are the most common.
Older Transformer or Lower Voltage Transformer
You may need to perform a voltage meter reading and possibly replace your transformer. (typically these can be found at your local hardware store for approximately $20).
Digital Door Bell Adapter Wiring Issue
If the chime is digital, please ensure that a digital adapter is installed with the SkyBell so that it can power up properly.
Poor Contacts between the wall plate
Check the back of the SkyBell and see if there is any bulging or arching on the backside of the SkyBell device.
Take off the SkyBell and check to ensure the metal contacts on the back of the SkyBell are not pushed in, this will also prevent the device from charging. You may need to turn the terminal screws slightly (one quarter turn) to the left in order to raise them up and make better contact with the SkyBell.