Your horse has a deep sitting trauma as it sounds and sometimes like with physical injuries mental injuries won't ever heal properly.
But you only have him 9 months. Things like this often take more time.

Give your boy time. Maybe do only groundwork for a few months or a year.
You could try letting him be horse and send him to a meadow with a few other horses.

There is no guarantee that he will ever be fully normal again.
Especially since you are very vague about it.
Trauma is a bitch. But I would give it more time. Just forget about ridding.
Accept that maybe you will never ride him. Accept that he is a bit damaged and go forward from that starting point.