Re: 2012 Tohatsu 15hp Starts in gear only has 1/2 throttle
What is your precise model/serial? The electric start motors have two safeties: recoil and electric. There is a neutral safety switch, as well as the mechanical pawl that prevents pulling the start handle. If both are not engaging (you can pull start or electric start in any gear), your shift linkage may be out of adjustment or disconnected. Likewise, if the throttle does not increase RPM above 1/2, the throttle cable may be maladjusted or disconnected.
If you prefer to check these things without a dealer's assistance, start by getting the Factory service manual (available from any dealer -- including me), and use it as a guide in checking/setting the linkages.