The built-in flash on my digital Canon Rebel XT (a.k.a. 350D) will not pop up. The camera body clicks whenever it tries to activate the flash, and pressing the manual flash release button doesn't work either. It displays an "Error 05" message, meaning something is preventing the flash from opening, but there is no apparent obstruction, and gently pressing or wiggling the flash assembly will not release it. How can I release it and correct whatever is causing it to stay closed?