<p>I have had a YongNuo YN468-II Flash for about three years, and it has received pretty light use. I last used it a couple months ago. When I got it out last week, I discovered that the flash will not fire. I installed fresh AA alkaline batteries. The flash powers up; I can cycle through all the menus; the red indicator light comes on, identifying that flash is ready for use. Yet it will not fire. Neither the Pilot (test) button nor either of my cameras (70D and T2i) will cause it to fire. The flash is communicating with the 70D when mounted, as it recognizes my changing ETTL settings or aperture. To my knowledge, the flash has not undergone any physical trauma since I last used it.</p> <p>I have also attempted to fire remotely it via transmitters.</p> <p>Is it just dead? Are there any troubleshooting options I can try? Is it possible to replace a bulb in these things? Thanks for any help. Let me know if there's any additional information I can provide that would be helpful in reaching a diagnosis.</p>