Not sure about the dsst (dstt?) but on the R4 when you get the screen with all your 'demo' games there's an R in a circle on the top right hand corner of the bottom screen, it'll either be red or green. If it's red, touch it & it'll go green. Now the soft reset - Left, Right, X, Y, A & B buttons all pressed at the same time - should work.
HH.