How to get Metabox custom field to show checked if value is updated using post meta query?

So your checkbox code works fine. But the problem is.. the meta key.

If you do var_dump( $meta['vmo_code_radio_value'] );, you’d get a NULL because the meta key contains a newline and it will be saved as is:

update_post_meta( $post->ID, 'vmo_code_radio_value
', 'enable' );

But if you do:

var_dump( $meta['vmo_code_radio_value
'] ); // note the newline

Then you’d see the proper value: enable.

So the fix is simple: remove the newline. I.e.

update_post_meta( $post->ID, 'vmo_code_radio_value', 'enable' );

And by the way, to retrieve a single value of a metadata, you could use get_post_meta(
<post ID>, 'key', true ) like so in your case:

$vmo_code_radio_value = get_post_meta( $post->ID, 'vmo_code_radio_value', true );