I replied when you first told us about this on FB and, again, I am so sorry for your bad luck. As I recall, your boat ended up trying to rest on its keel in that shallow water until it fell over. And, indeed, it seems like it may have been one of the O'Days with the thin FB layup at the keel. Otherwise it probably should have just fallen over into the water and mud. But, in fairness to the surveyor, I don't know how widespread the knowledge of this weak point is outside of O'Day owners. It's not necessarily something a surveyor would be able to spot from tapping and inspecting the hull, etc. Owners have only found out about this the hard way and, even at that, mostly thanks to the web.
I hope your son returned your wallet and made good on the money he took. I also hope things go much better with your replacement boat. As we talked about on FB, it might be helpful for you to read up on some methods for securely setting the anchor so that you are less likely to drag in the future. It has happened to many of us, I imagine, but it sucks. Wishing you the best.