MBP 2015 bricked when upgrading to Sonoma, stuck on boot screen with ~5% loaded. Plz advise

I have a MBP 2015 that I upgrade to Ventura using open core about 8 or so months ago. All was well for a bit.

About a month ago, I was using it and the open core dialog popped up and asked about an update to sonoma, foolishly, i said yes...

Since then, it's essentially bricked..

It now stays on the apple logo screen with about 5% of the white bar filled, and won't go past it.

I've tried every combo of booting and got no where.

any help and suggestions would be so appreciated.

Ty in advance