[L473ncy]

It looks like your tamiya connector is fucked. Looks like the wire fell out of the "wing"

Go to a hobbystore and get a set of new connectors (I don't think they sell the wings individually). That or go ahead and change over to something like Deans. It's easy enough for you to do that and that will fix that.

Also, correlation does not imply causation. Your battery connector and the trigger assy. are two different systems. Likely your cutoff lever is worn or there's something wrong inside your trigger assy. If thats the case and you're not confident enough to do your own work find someone else to do it for you.