I have a large matrix that represents tabular data, and I need to find the row where a specific value exists in the first column. Here is a simplified version that give the same compile-time error, CS1503, “cannot convert from ‘object[,]’ to ‘?[]'”

object[,] mx = new object[,]{{"ABC",123}};
var f = Array.Find<>(mx, x => ((string)x[0]).Equals("ABC"));

I suppose I could iterate, but there must be a more elegant way.
I tried different LINQ queries, but not get any to compile.

Kevin