Photos Library Not Repairing

You wrote "So I controled-option-double-clicked to initiate repair."

To start a library repair you need to use the shortcut ⌘⌥ option-command and not ctrl-option. Have you done that?

Hold down the key combination ⌘⌥ firmly while double-clicking the library you want to repair.

Release the keys, when the repair starts.

If all else fails there is a possible way to recover the library if you don't have a Time Machine backup of it made just before the problem started. However, it will require the purchase of PowerPhotos which is the best Photos library utility available (my opinion). It would work like this:

1 - create a new, empty library on the EHD.

2 - launch the paid version of PowerPhotos and add the new library and old library to its sidebar.

3 - do a merge of libraries using the new library as the destination and the old library as the source.

4 - when completed open the new library and confirm that it has ALL of your photos and videos.

You can also create a new library with Photos and import the old library into it with Photos but would not get all of your organizational effort brought over, i.e. albums, etc.

A comparison of the differences between Photos and PowerPhotos in merging is described in this user tip: Merging/Importing iPhoto/Photos library into Another Photos Library: PowerPhotos vs Photos

Is the name of the Library correct? This is the default name for a Photos Library. Maybe Photos is looking for the wrong Library?

Can you double click on the Library package icon on the external drive and have the Library open?