Is this the proper way to run a transient simulation on a thermal 3D FEM with the PDE toolbox?

 How can I model a 3d FEM and run a transient simulation?

 I've tried this so far and it doesn't seem to work

The real question is how do I run a 3d transient FEM? And view the result this doesn't work.

thermalmodel = createpde('thermal','transient');
gm = multicuboid(1,1,0.5,'ZOffset',0.5);
%if this doesn't work choose your own geometry
thermalmodel.Geometry = gm;

%%%%%%%%%%%%%%%%%%%%%%%GENERATE MESH %%%%%%%%%%%%%%%
% meshsize = 0.4;%mm                           
meshsize = 4;%mm                           

generateMesh(thermalmodel,'Hmax',meshsize/1000);
thermalmodel.Mesh
pdemesh(thermalmodel)                           

htc = vpa(25) *u.Watt/(u.m^2*u.Kelvin);
htc = rewrite(htc,u.Watt/(u.in^2*u.Kelvin));
htc = double(separateUnits(htc));

thermalBC(thermalmodel,'Face',1:thermalmodel.Geometry.NumFaces,...
'ConvectionCoefficient',htc,'AmbientTemperature',288.15);
thermalBC(thermalmodel,'Face',1,'Temperature',50+273);%bottom face

mybc = @(region,state) sin(350*state.time).^2;
thermalBC(thermalmodel,'Face',12,'Temperature',mybc);%top face

tfinal = 6;
tlist = 0:3:tfinal;
thermalIC(thermalmodel,0);
thermalmodel.SolverOptions.ReportStatistics = 'on';

result = solve(thermalmodel,tlist);

figure; pdeplot3D(thermalmodel)
pdeplot3D(thermalmodel,'XYData',T(:,end),...
'Contour','on','ColorMapData',results.Temperature); 

title('Temperature in K')
colorbar

pdeplot3D(thermalmodel,'ColorMapData',results.Temperature); 

axis equal
title(sprintf('Transient Temperature at Final Time ...
(%g seconds)',tfinal));

[Steven]

change the mesh to a larger size if it wont run on your machine