Cannot update site to 8.5.1 using composer and drush

I have always manually updated my drupal 7 site, but recently moved it to Drupal 8.4.  Now I need to update it to 8.5.1 for the new security fix.  I am trying to do that following the recommended procedure using composer and drush but have not succeeded.

Background:  I really didn’t know what I was doing, but on a local Windows Hyper-V virtual machine, I installed a drupal 8 site using Bitnami, then installed another site using composer. Then I used composer to install drush.  All that seemed to work.  (Thus C:Bitnamidrupal8 has composer and drush installed, and a drupal 8 site at ..appsdrupalhtdocs  and C:drupal8 has composer and drush installed and ..web has a drupal 8 site)  I think this will let me develop in the C:Drupal8 folder, then use composer to INSTALL my changes in the bitnami folder, and eventually move it all from the local machine to the web.

I then tried to follow the document  “Update core via Composer : Drupal 8 guide”

Step 1.  I did a CD C:Drupal8 then the command composer update drupal/core –with-dependencies.  That seemed to work.  (At least it downloaded updates for twig and another package), but I’m not sure it downloaded 8.5.1 and don’t know how to tell.  I did try the composer prerequisites command,

Step 2.  The command drush updatedb gave  me an error.  So I used composer to install drush.  Then I tried php drush updatedb, which gives me a “Cannot find input file” error.  Since then I have spent several hours searching the documentation, googling, etc.  I have tried a variety of things, including modifying the path, using the full path, etc.  All I get is  “could not open input file”.

Two questions:  How can I determine if composer downloaded 8.5.1?  and How do I fix the drush “could not open input file error”?

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