Could it be that because of the turbulence (let us assume it was turbulence at this point in time) that the aircraft switched from normal law (I guess) to
abnormal law (abnormal alternate law) which more or less means manual flying.
As for the captain announcing to the pax about "computer failure" - is this an easy way of explaing Airbus control logic to pax?
E145 driver moving to A32x...