For Samsung phones there is Kies which is used to upgrade or downgrade the firmware on your phone. If you still can open your phone, you will need to put it in Download Mode using Volume Down/Up + Menu + Power. Once in download mode you can use a 2.3.6 ROM from Samsung Update and Odin 4.43 (this version specifically). You can use Heimdall One-Click Unbrick to enter Download Mode. Attach the phone to the computer and run the application. Make sure you have the latest Java Runtime installed.