How to enter samsung galaxy s plus i9001 in download mode

i9001 has 4 physical buttons:
- Power 
- Volume Up 
- Volume Down 
- Home
and two touch-based buttons:
- Back 
- Menu



Entering into Download Mode

• Download mode is used to flash new ROM or custom ROM firmware.
• To enter download mode, turn off the phone and then hold down Volume Down + Home + Power.
• If done properly within 1-2 seconds you should see a screen with the green Android robot and the writing "Downloading... Do not turn off target!"
• Pressing Power for at least 8 seconds will reboot the phone.
• If you can't enter the download mode your phone might be Soft-Bricked.