I have finished the body topology by closing the holes of the neck, the abdomen and the throat having a half of the model. Then I applied a symmetry to create the left part of the model. Topogun doesn’t merge the vertex in the centre plane by default so I had to merge one by one moving them and the recentre those vertex to the centre plane. In this phase I started to tweak the vertex by using the relax brush and modifying not wanted pools, mostly created in the symmetry plane of union.
With the body finished I started with the rest of the elements. I first did the “elements01” group consisting in the nails, the plates of the wrist and knees, the tongue and the glands. I imported the high poly mesh as the reference and this time I used the low poly model to work on it by deleting edge loops and correcting the spiralling by moving edges and reconnecting them in the right loop. If nothing mentioned worked I did it from zero.
For the back protrusion I had to start from scratch as the low poly model was useless. As it is a non-symmetrical object but it shares the same base I did the retopology of the left part and then mirrored it and adapt it to the right model, redoing the top part as it is where the difference is.