Few user reported an issue most likely the Native instruments application blocks the firmware update because that application blocks the driver. You need to kill that process manually using your task manager on your MAC.
If you have no native instruments installed, or you cannot find the process please follow this instructions:
0. Disconnect your LP-16.
1. Please find and start the “Automator” app in your launchpad.
2. Choose the “Application” in the Automator
3. In the search field type “quit” then select “Quit All Applications”
4. Make sure the “Ask to save changes” checkbox selected
5. Command + S –> or “File” -> “Save” name your application “Quit all applications”
6. Connect your LP-16
7. Start the USB updater and click on the update button