Hi, just to give you an update. My Giant is working again for some weeks now. What worked for me is to clean the whole boards with isopropyl alcohol. This worked for me when repairing my old smartphone and it helped here too. After cleaning I let it alone for some days and it worked again. I don't know if the isopropyl was the solution or if it would have worked anyway, but you can give it a try.
But earnings are very, very low with the giant now and I'm not sure if it's worth bothering with it anymore.