Remember, if one of the child xrefs is corrupt, then this will affect your main drawing also. In the past, you would have to run RECOVER on each child drawing. If you had several xrefs, you might even have to open the main drawing and make note of the path and name of each drawing.
With RECOVERALL, you simply pick the main drawing and it, along with all the child xrefs are fed through the RECOVER command. All errors are fixed, and each drawing is saved in the current format.
The first time you run this command, you will get this dialog.
Press Continue and select the main drawing. After the process has completed, you will be presented with the Drawing Recover Log which will look something like this.