hey, did you try your starter b4 you installed it?
manual said you should test it b4 installing it. as to the ECU, there is no separate ECU for it instead it is connected to the body ECU and ECM via ST. just to make sure this is not st make sure there is continuity between terminals 1 and 2, they are the ones that located like this 1| |2 while number 3| is below and no continuity between 3 and 5 which are 3-|5 . check the operation as well
apply poweer to ternianls 1 and 2 and check that there is continuity between 3 and 5. if it all ok then might be smth else. also this click ing troiubles me. did it just click but doesnt spin at all? click means that the pinion gear comes out and connects to fly wheel. sometimes thie pinion gear is broken and starter just spins. let me know of the results and specifics of the clicking