I knew about the problems when I bought it. I can't say the humming problem was an easy fix, but polishing the screw on the bridge did the trick (it was pretty hard to remove the paint, but after that everything was fixed).
After that, I observed that the battery was discharging in fewer than a month (the cable wasn't plugged in), so I have disassembled the output jack to find out the DISASTER: only two cables were present, no grounding. The black cable from the battery was directly connected to the sleeve of the jack, no wonder that the battery was discharging. Also, no ground is present on the guitar.
For a learning (to solder and repair guitars) is a good guitar, if you set it up correctly it sounds great. If you buy it, you will have some work until you make it "perfect". Good that I haven't found problems with the frets.