Couldn't find procedure for start/stop engine switch replacement on Yeti, however this might be useful to others.
Problem was start/stop switch was intermittent, spraying with contact cleaner worked but not for long.
The steering cowl is in two halves, drop steering wheel to lowest position and prize off top one by hand or aided with blade between halves. Lift up out of the way which is restricted by fabric cover.
Remove torx t25 screw underneath lower cowl and then remove two more screws that are exposed fully when steering wheel is rotated through 90 degrees left and right.
With screws removed lower cowl can be dropped down and access to the switch to be replaced is now easily possible. Undo plug with locking tag and push switch out.
Reverse procedure to reassemble.
Good luck !!