I was getting the the E04 "safeguard mode" error, too. Bought another camera for tomorrow's Christmas program at my daughter's school. Thought I'd give the JVC one last chance and saw this post. Camera off. Tape out. Door closed. Gave the JVC a couple of really good whacks - hard enough to make my hand sting for a few seconds. What do you know? Works like a champ. Hope I don't have to repeat this repair procedure in the middle of my daughter's program.
Glad Costco has a good return policy so I can return the Canon ZR85 I bought to replace the JVC (just read some reviews of poor indoor/low light video quality).
Thanks, Jeff, for posting this repair procedure!