Here's the release notes for the 2.4 firmware update:
Version 2.4 - June 4, 2015
•Fixed EDACS patching bug.
•Add delay in USB startup required by some USB host hardware.
•Changed algorithm used for battery level icon.
•New default voltages for NiMH icon thresholds.
•Fixed Audio Boost handling for analog frequencies.
•DAC gain changes for digital "too loud" problem
•EDACS ESK detection fixes
•Fixes for password / alarm functions. Changes were not always preserved on power-down.