What does a solid red Service LED mean on the BGW320-500?

A solid red Service LED indicates the device is overheated or has experienced a POST (Power On Self Test) failure. If it is a POST failure, alongside a solid red WPS LED, the gateway has a hardware issue such as DDR read/write failure, Flash read/write failure, or System Power Good failure, and may need replacement. If the device is overheating, it should be moved to a flat surface with sufficient airflow around it. (Page 18, 19)