Kicker motor repair needed

[Schuster]

I was asked by a friend who inherited the boat to help him fix his kicker motor. The situation is this; The motor is a 2016 T9.9 Yamaha, electric start, hydraulic tilt. The boat sat outside for a couple of years with the kicker motor in the tilted up position with the tiller arm up (and catching all the elements rain, pollen, sun etc} the tiller arm is stuck in the up position due to what i'm not sure. Not being familiar with the operation of these motors i'm not sure if there is a latch which holds the arm up or if it is frozen shut for some reason.
The motor appears to be in great condition and I dont see any signs of rust etc. I used a heat gun to try to free up the hinge joint in case it was solidified grease without success. Im sure it is probably something simple that I just don't know about. Does anyone have any ideas what may cause this? Anyway thanks for any help.