Hi there,
As you have mentioned in your detailed job description, you have tried almost everything possible that you can. But I think I can help you on this issue, at least I can try my best.
All we need is:
1. disable the default keyboard in any way.
2. Anyhow, restore the system to its previous condition, when the keyboard drivers were not installed by you.
I would really like to take this challenging job.
By the way, your system is not booting, so no chance for a remote session. Then how will we proceed? Over whatsapp or any other chatting platform?
My suggestion, I will guide you through chat and you will perform the steps.
I can do it right now, just waiting for you reply. Or you can suggest any time as per your availability.
Thanks