On the A2+ Wireless/HD3 models with an external power supply brick, first test it by plugging into wall power and observing the LED light on the brick to see if its solid, blinking, out. If it's blinking or out, the power supply is likely faulty.
If the light is solid, proceed to plugging into the speaker and observe the power supply brick LED once more. If it's blinking or out, there is likely an issue with the internal amp. Contact support if either has an issue.
If the light is solid, proceed to plugging into the speaker and observe the power supply brick LED once more. If it's blinking or out, there is likely an issue with the internal amp. Contact support if either has an issue.