There is no battery in the Irig2 HD. The light is simply a power/signal light. From the manual:
iRig HD 2 status LED The LED on iRig HD 2 gives you important information about the iRig HD 2’s operative status. Each status is indicated by a different color: • LED is off: iRig HD 2 is not connected to any power source. • LED is dark blue: iRig HD 2 is connected and in standby mode. • LED is bright blue: iRig HD 2 is connected and active. • LED is green: iRig HD 2 is active and the input signal is low. • LED is orange: iRig HD 2 is active and the input signal is OK. • LED is red: iRig HD 2 is active and the input signal is too high.
Hey, thanks so much for that clarity. My problem lies in that I only received a quick start guide which does not explain as you did. I did find however, in my account that there is a manual to download.