If it's like my M900 (i.e.) tank, then the pump is just held in a spring loaded clip and so pulls out easily and IIRC the power cable is a simple 2 pin plug though there maybe a simple lock/clip mechanism, I can't remember?
Best to undo the hoses and remove the whole assembly, like this;
But it is a job to get at due to the small opening and tight angle so expect scuffed wrists.
Much better the system used in 916 etc. where a removable plate is fitted to the underside of the tank and the whole assembly simply pulls out.