If the EPC can boot but Drive D is inaccessible, it can be restored from an archive on Drive C to be like it was when the EPC was first shipped from the factory. Drive D corruption can be caused by improper shutdown, often due to issues with unresponsive UI (see 
Software Startup Failure & Recovery ( https://roos.com/docs/RBEH-8WK9KW?Open )
WARNING: Following the procedure below will erase any data on Drive D. This is OK if the data is backed up to Guru server, but may loose recoverable data. Please contact [email protected] for details.
To Restore Drive D:
- If the OS Desktop is not accessible after booting, follow the steps to enter a command prompt Recovering System Configuration with ALT+F1 - Recovery Choices ( https://roos.com/docs/RBEH-8V92FA?Open ).
Otherwise open a command prompt window by choosing Command Prompts > Command Prompt (Window). - From a command prompt, type:
format d: /fs:jfs - When it prompts for the drive label type:
application - When ask for a new label type:
application - After the format is done; type:
d:
unzip c:\RI\Drive-D - After the files is restored, type:
unzip -o GuruKeys\<the system Guru ID> - If the Deskop is not visible (i.e. recovery prompt used in step 1 above), then reboot. Otherwise continue on to the next step.
- From a command prompt, type:
cd RiApps\guruServer
startApp -RiBackupGuru <your backupGuru Server IP address> -RiUpdateGuru <your update Guru Server IP address> - Choose Logon on Guru, enter User Name and password.
- Choose System > Restore to copy the latest version of every object with ri.sys.Owner = Guru ID to the local Guru.
- Re-boot the system, following standard shut down procedure. (ArcaOS > Shut Down)