I had this same exact issue yesterday. I've had my enertiia 6 months after I bought used with 1600miles and added 800 miles on daily commutes with no problems. Suddenly yesterday I had the issue of bike accelerating on its own on the street and this only happens once the bike is going 10mph or so. Absolutely no physical throttle stiction, only electrical issue. Throttle close does register zero for starting purposes. I was able to apply brakes a bring bike to stop. When bike is traveling below 10mph roughly throttle does cut back, but once it starts going above that speed it keeps going, worse when I'm going downhill. I managed to get home safely with frequent braking, which discharged battery faster. Several stops restarts did not fix the issue. This problem came up suddenly between daily commutes, only possible reason I could think off was a mild shower or dew in San Mateo hills where I live that could have wetted the throttle on an uncovered bike, but it was nothing unusual in weather past day. Also on second screen toggle while riding, I noticed a vertical bar in power display which seems to indicate highest power reached as in cruise control. But self acceleration goes beyond this level and sets a new high all the way to 100%
Calling brammo today to find the fix. Live just beyond range from dealer in San Francisco.