SO, is your problem that you want to solve, the clicking noise? Or the no response from throttle? Is this the same problem as it stopped working on the new bike, or is that something else?
How old is it, how much do you weigh, how much did the previous owner weigh, how long did he have it, did it ever work when you owned it, how long have you had it, has it gotten wet, and did anything unusual other than the clicking noise ever happen in your presence?
Does anything light up when you plug in the battery, is there a voltage readout on the throttle, does the throttle have any lights at all, is there a power indicator on the battery, have you turned it off, then on again after the click, and how long have you waited to test again after the click?
I have more questions, but we'll see how you do with those.
All of that, ALL OF IT, are things you should have supplied in your very first post, in order for YOU, to get YOUR PROBLEM, solved.