No telling what version firmwater is on your esc - get Castle Link and install the prgm on a PC and then update the Mamba. I have 6 25s and with all but 1st one, I updated them first, then calibration was nothing. The one I tried to calibrate 1st - same deal you're having, trouble.

These escs seem to be easy to put into progtramming mode without realizing it too and thats usually whats going on when you get no repsonse - you're in prgm mode. Link and PC eliminates all the confusion and trouble.