To gain access to the Moai, you must die nearby while you still have the Ankh in your inventory. The most reliable way of doing this is to simply commit suicide while the statue is on the screen. Obviously, this destroys the Ankh but grants you access to the inside of the statue, where the Hedjet lies in front of a secret exit. Do not attempt to use a bomb, as the persistent blast may kill you twice in quick succession, before and after the resurrection.