The only time I ever got a red light on my Sirius charger was when
the input voltage to the charger was too low. So check to be sure
your power source is up to the task.

If that checks out then there is a possibility that you have a connector
or charge cord problem. If the charger cant "see" the battery you
will get a red light.

Also a defective battery that reads very low voltage will do that.
Verify your pack voltage with a meter.

If all the above checks out then you may have to send it in for service.
But I bet the problem is not the charger. Its such a reliable and well
built piece of equipment. But you never know.

Mike Hammer