Motorcycle Questions? Ask a Mechanic.
Hi and welcome to JustAnswer,Thank you for the question and your patience. Should you still need assistance for information purposes only...Initially and if have not been tried; inspect the battery & ground lines and/or check/clean the battery cables + terminals as a preliminary consideration. Better yet, have the battery externally charged and then LOAD TESTed (even if new and just for the purpose of eliminating it as a suspect).
Then, check (or better yet, replace) the starter relay. To locate the starter relay, start by following the big cable from the + terminal of the battery as it always ends up tied to 1 of the 2 big terminals of the starter relay. Carefully but quickly/momentarily jump the two (2) big terminals. This is a bypass of the starter relay to enable the starter motor to spin:
Please post back results / observations of the above once tried.