When he reached the end of Anglesea St, Mr O'Connor entered the property of 1 Angelsea St, walked about 25m down beside the house, climbed over a raised garden bed before losing his footing, grabbing hold of a portable compost bin and falling to his death down an approximate 6m cliff on to the road below.
He was found by two students just after 1am.
During the inquest, Mrs O'Connor said the area where her son died was a "death trap" and urged that fencing be erected to prevent a similar death in the future.
They accepted that their son was drunk and disorientated after being in Hamilton just 36 hours.
But in his findings released today, Mr Matenga found Mr O'Connor's death was accidental.
"Even though it was the middle of the night, there would have been sufficient light for him to be aware that the ground was dropping away sharply. Sean was where he should not have been and made a serious error of judgment. While I can accept that a fence would have prevented his death as suggested by Mrs O'Connor, I do not accept that erecting a fence is necessary."
Mr Matenga said the circumstances of Mr O'Connor's death were "unique and are unlikely to be repeated" and declined to make any recommendations.
"Sean would not have been aware that a short distance further along the bank became an almost vertical crib retaining wall. Sean has lost his footing and fallen to the roadway below causing a number of injuries which led to his death."