Further to that, found the actual quote (from another chat site):
"I haven't touched a V2500 powered A320 in 3 years, the fleet I work on now all have CFM's. The lockout procedure is to deactivate the HCU (hydraulic control valve) of the affected engine and then to secure the sleeves closed mechanically. After this is done you then have to check for specific messages via the CFDS (on board maintenance system) if none of these specific messages are present the aircraft can be dispatched as per the MEL.
"As the HCU is physically deactivated the system can't pressurise. If the circuit can't pressurise then no pressure signal is sent to the EEC (FADEC) and the engine cannot power up to the max reverse setting as all the imputs to complete the system logic are not present."