SSD USB-internal boot voodoo magic?

[wowzer]

I have a SSD (ADATA) that I used to boot a MacBook. It was working just fine, until my daughter pushed the power button and held it down to turn it off. Now it won't boot-just the folder with the question mark...hang onto the voodoo strangeness:

I put a different SSD into the laptop and it worked just fine (10.13.6). When I put the 'bad' SSD into an external USB enclosure, I can see the drive (running 10.14.x). I can even use this external SSD to reboot from the laptop. When I reinstall the SSD back into the internal, I get the folder with the question mark.

Is there something that I should do to fix this?

Thanks

[wowzer]

it would seem that the restart/shutdown method still uses the internal SSD as a startup, then switches to the external 'bad' SSD.

How do you reinstall OSX without erasing the user content?

[pdq]

wowzer wrote:

How do you reinstall OSX without erasing the user content?

Others can correct me, but I think that's an option when you're installing any MacOSX.

Did you run DiskUtility on the problematic drive?

[wowzer]

diskutil output the file system check exit code is 0.

[modelamac]

Unless something has changed and I missed the notice, no data is lost by installing an OS over an existing OS. I rarely do a clean installation. Ninety percent of the time I just update the existing OS. I have often re-installed because something did not go right the first time.

wowzer wrote:
it would seem that the restart/shutdown method still uses the internal SSD as a startup, then switches to the external 'bad' SSD.

How do you reinstall OSX without erasing the user content?

[wowzer]

modelamac wrote:
Unless something has changed and I missed the notice, no data is lost by installing an OS over an existing OS. I rarely do a clean installation. Ninety percent of the time I just update the existing OS. I have often re-installed because something did not go right the first time.

[quote=wowzer]
it would seem that the restart/shutdown method still uses the internal SSD as a startup, then switches to the external 'bad' SSD.

How do you reinstall OSX without erasing the user content?

Thanks. I will try to reinstall the OSX. Backing up data first...not so easy as it would seem as I need to get another 10.14.5 volume before i can migrate the user data.

[wowzer]

Migration complete. Now I can try to reinstall Mojave on it.