Difference between locked and dead objects in Modernization Workbench queue
Locked records means the HCC ran into errors while processing the particular object. In this case, the error probably resides with the file itself.
Dead records means the HCC failed in the middle of processing an object. This can happen if the tool crashes, or the connection to the database is lost during the processing. In this case, the error likely resides in the environment.
In either case, the recommendation is to delete the locked/dead entries from the Queue and then re-verify them in order to place back into the Queue for processing by the HCC.