Thanks for your reply BillO
I tried changing the board type to UNO and Arduino Mini, this time it fails straight away: no reply at all from the Arduino. I tried to change the baud rate in the avrdude command line parameters, the only that gives any result is 57600 (result as showed in my original post).
Unfortunately I do not have any ISP or other Arduino to upload a new bootloader. I think I will buy a cheap one from ebay and see how it goes (like this one : http://www.ebay.co.uk/itm/USB-AVRISP-mkII-mk2-clone-ATMEL-AVR-New-/150584815125?pt=UK_BOI_Electrical_Components_Supplies_ET&hash=item230f8dee15)
The board is brand new, I'd be pretty unlucky if it has the wrong bootloader in it or if it's corrupted 