I had a nice Vamo V3 that stopped working about a year ago after a month (my third one, I own a wholesale juice business, so I literally have over 40 different pv's I switch back and forth with, and always have to buy new ones (or at least feel compelled to). Anyways, after reading this thread I took a screwdriver and scraped away the red spacer inside the battery chamber up by the post. Fn works good as new! Super stoked, because they had already sent me a replacement for this one last year and I left that one in a cab in Portland. Glad I found the post on this thread. Thanks!