Can't get past the PIN-screen of my newly bought used S4 I recently bought a used Samsung Galaxy S4. The problem is that the previous owner did not factory reset is and even after putting in the memory and SIM-card from my old phone, I can’t get past the pin-code screen. I have tried factory resetting it myself, but it isn’t working. What do I do?
So you have resetted the device? 
Or was the resetting to factory defaults not working? 

Boot into the recovery ( volume UP + power button - press both until the screen turns on and release the power button then) and then perform a factory reset from there. This should delete all user data and your phone should restart to the initial startup configuration.