Normally when pressing ONLY POWER button, grinder works. One morning it stopped working. When pressing POWER, there is...

I would suggest doing a search here at iFixIt for “Samsung Mini S4 charging” for some good ideas. A couple of the Guides mention replacement of the Charging Port Assembly - which is what I had to do for both my Mini S4 and another brand of phone with same problem (my Mini S4 would not charge after IC replacement. It finally needed new Charge Port connector, and the Nokia phone originally needed the charging jack replaced, which I did, then later got entire charging assembly replaced)