Your bootloader is damaged. You need to flash a full package with a preloader. Look for a “Complete Firmware Pack” containing Partition.mbn .
You can download the latest official stock ROM for your region from repositories like Sfirmware or SamFrew . samsung gt-c3520 flash file and tool
in the CSC section and select the corresponding CSC file for your region. Connect the Device Turn off the phone and remove the battery Press and hold the 1 + 3 keys (some guides suggest ) on the keypad. Your bootloader is damaged
One by one, he loaded the firmware files into the tool—the Main Partition and the CSC file—mapping out the phone’s new memory. The Handshake: samsung gt-c3520 flash file and tool