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
/config/custom_components/onkyo_serial
ren media_player.py to onkyo_serial.py
created a manifest.json with requirements
created an (empty) init.py

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 media_player.py in a directory called onkyo_serial