The Samsung GT-C3520 is a classic dual-SIM feature phone from Samsung’s early 2010s lineup. It runs on a proprietary RTOS (Real-Time Operating System) with a Java-based interface. Over time, devices like this may suffer from boot loops, stuck logos, forgotten passwords, or IMEI corruption. The only solution in most cases is to re-flash the original firmware (also known as the flash file or stock ROM).
Flash File (Firmware): You need the stock firmware specific to your region or carrier. samsung gt-c3520 flash file and tool
Before starting, ensure you have gathered the following files: Samsung GT-C3520: Complete Guide to Flash File (Firmware)
The progress bar will turn green once the process begins. Wait until it displays "All files complete" or a green "Done" status. : Disconnect the USB cable and power on the device. Device not detected: reinstall drivers, try another USB