This is for the battery on the Vision or ProMotion control in the back cabinet. It will be displaying ALP-EN to show that its battery needs replacement.
The full manual for the drive is posted in the "Tec-docs thread" as well as a link in the other info dump that has "Every Doosan Service manual"
I try to have every piece of information you will need available, even before you know that you'll need it...
If you have more questions, my cell number is in the footer of each of my posts. Please call.