You will need the specific .FFU image for your device's product code. How to Install a Custom ROM: The General Process
Searching for ROMs online brings up a lot of fake links. Let's bust some myths: Nokia Lumia 520 Custom Rom
The first boot after flashing a ROM can take up to 10–15 minutes. Be patient and keep the device plugged into power. Why Mod Your Lumia 520 Today? You will need the specific