DIAGNOSIS The triple beep is the washer's way of saying "you haven't met all my prerequisites to start." It's not an internal fault code like F01.
FIX Run down this checklist: 1) Is the door firmly closed until you hear a click? Give it a solid push. 2) Is the water supply (both hot and cold taps) turned on all the way? 3) Is the drain hose inserted properly into the standpipe or sink, not pushed in too far (which can cause a siphon) or kinked? Fixing any of these usually resolves the triple beep.
IF THAT DIDN'T WORK Check the drain pump filter for a clog. A blocked filter can prevent the machine from starting because it can't verify proper drainage. You'll find it behind the small access panel at the bottom front.
HEADS UP If you've recently moved the washer, make sure the shipping bolts (the large rods that go through the back) were removed during installation. The washer won't operate correctly with them in, and it can cause a violent imbalance.