Custom component not working after upgrade

I upgraded from a fairly older version (I think .90.4 or something) do the latest yesterday. After this, I have a custom component that does not work.

I saw the changes listed and changed my custom component as follows
ren to
created a manifest.json with requirements
created an (empty)

After that, I get the following error when doing a hassio homeassistant check

Error: Testing configuration at /config
Failed config
  General Errors:
    - Platform not found: media_player.onkyo_serial
Successful config (partial)

It should be in a directory called onkyo_serial