Please, use </> button to share codes, terminal outputs, error messages or anything that can contain special characters which would be interpreted by the MarkDown filter. Use the preview feature to make sure your text is formatted as you would expect it and check your post after you have sent it so you can still fix it. I edited your post.
This is not getting into the container but starting an existing container which fails. Can you show how you created that container?
Then it is probably because you mounted a device file which only exists until you restart the container. This is why it is important to see how you created that container originally. If you don’t remember, please share the output of:
docker container inspect a4ba5a6a6ab4 --format '{{ json .Mounts }}'
If you have “jq” installed on your system, then please, run this command instead:
docker container inspect a4ba5a6a6ab4 --format '{{ json .Mounts }}' | jq
and use the </> button when you share it of course 
However, you should not create containers that you can’t remove safely and create it again. If you mounted a device which is not there now, you need to remove and recreate it the container. I think there is an other way too if it is absolutely necessary, but I don’t remember it exactly and it requires editing files in /var/lib/docker which is not really a good idea unless you are experimenting in a test environment.
When you fix the container, then you can use docker exec to get into the container.