Do you still have a copy of the object before you chopped it with the cylinder?
Firstly, It is still too small to work with properly!
All the random triangles you have used to mend holes is the wrong way to go about it. Turn on hidden geometry and join the dots, simple long edges from point to point will close the holes smoothly.
But If you had scaled up before trying to intersect it with the cylinder you probably wouldn’t have needed to repair those faces to begin with.
As it stands it is quite some considerable work to repair and make into a solid, it is possible but time consuming.
If you have the original and it doesn’t have all those random triangles, use the Dave Method and try again.