16V requires timing pulses from the crank (sensor behind aux belts) and the cam (sensor by battery). Check the crank pulse for clearance and dirt (1mm from memory) and for broken/chafed wires, and this needs an oscilloscope, for the double(?) pulse from the cam sensor. It's also possible for the cam to move on its mount, but unlikely.
A failure of either signal will cause non-starting, but an intermittent signal might cause a mis-timed signal from the ECU. A large earth pulse through the starter current might indicate a poor earth somewhere.