Great to hear it boots up now!
There's two different cracks available. For the older one, you'd replace the "control.asc" file on the Mackie OS harddrive, but then you would still need to use the authorization codes from somewhere on this forum, to unlock each plug-in individually.
There's a newer crack available, where you only need to replace the "MackieOS.EXE" file on the Mackie OS harddrive, and all the plug-ins will already be authorized. Sounds much easier... but I authorized mine a long time ago, before the new crack was available, so I have no personal experience with the new crack. Several people on here confirmed that it works successfully, though.
Here's a link to the download and instructions for installing the new crack:
viewtopic.php?f=2&t=1634&hilit=crack&start=150
You HAVE to use either the old or the new crack, or have the original authorization codes for YOUR specific D8B (the original codes are locked to an ID in a chip on the D8B. The crack bypasses that, so that authorizations work on ANY D8B, regardless of it's unique ID).
Assuming that you don't have the authorization codes for YOUR D8B, but want to run Mackie OS 5.1 (highly recommended), then it's necessary to follow the instructions for one of the cracks mentioned above.
Mackie OS 3 works without a separate authorization, btw. But you don't get all the features/plug-ins with this version.
Again, best of luck!