Because the filesystem is encrypted, it cannot be accessed using most tools. In order to access the files, the encryption driver must be active and the key used to encrypt the disk loaded into the driver.
Using a WinPE disk created following the steps outlined in DETech User Guide (PD24871), after authorizing and authenticating, the filesystem of the disk can then be accessed.
The other method is to decrypt the disk using the DETech Stand Alone to decrypt the disk and then use any tool that you would normally utilize to correct the issue.
At this point being the machine is already in the process of decryption, I would suggest that it finish the decryption process using the stand alone disk and a WinPE DETech disk be created for any future issues.