I have been working on my sons ATV Coolster 125cc 3125CX2 and all of the sudden it won't start.

I first replaced battery as original one was not holding charge but when I tried to start it solenoid clicked once.
Next I figure to replace solenoid and starter but when I tried to turn it on same thing, solenoid clicks once.
I have tried to jump start by connecting solenoid post to each other but I get no spark. I have replace solenoid at leat 4 times thinking I have received faulty once from Amazon or local parts store. I don't know if it could be something electrical but power does seem to run as brake lights turn on. I have been trying to figure this out for a while and could use some help.
Any advise would be great as I tired of ordering parts that may not need too.