So this is what I did. I took the SSD out of the P4. I hooked it up direct to computer. You’ll need to plug it in to a sata connector on your pc or laptop or use a sata to usb adapter like I did. Make sure the drive has the same Letter that you use for your Engine or Engine DJ 2.0 install. BTW if you haven’t installed 2.0 yet, do so once the drive is connected, as previously mentioned. Then run Engine DJ on the PC and let Engine DJ do the conversion of the Database. If you are still having a problem with the P4 Engine Library then copy a backup of your engine library in place of the one you are having a problem with on the P4 Drive. It goes so quickly and I have a 2tb SSD loaded with 185,000 tracks and it runs like a charm now. The first time I booted, the fixed database in the P4 it asked finally for my user profile to be loaded but froze for a couple minutes then all of a sudden the rest of the 2.0 update installed. I guess the checking device stage was keeping it from finishing. After that everything was there looking pretty. Hope this helps.
I am having the exact same issue as you. And taking the hard drive out isn’t really a option for me. Desperately need to restart the update or roll it back