Have tried volume up, home and power button but it just continually vibrates until I release either the home or power button and starts up into safe mode.
Make sure that your phone is turned off first.
Then, hold down all volume up, home and power until you see the Samsung logo appear. When you see this, let go of the power button and carry on holding the other two buttons (volume up and home). You can let go of these buttons when the recovery mode menu appears.
Hope that this helps!