Cable you need to flash this model of Samsung is C260 NSpro cable and battery must be out of the phone.
Run NSpro software program.
From model list Select C250 and click on Next button.
Click on Flash button.
From Baudrate drop down menu select 921600 for faster process.
UnCheck Repair Mode option.
Click on Browse button beside Write File field and select: C250xxxxx.s3.
Click on Write button and connect Cable to phone to start the process.
Do not touch or remove cable or battery from phone till all is done.
Notice: In case your phone has some software problems you can flash it with Repair Mode option Checked but you will lost the IMEI number of this phone so after flashing process finished you need to rewrite your phone IMEI again.