My D80 had a similar problem, displayed Err, wouldn't auto focus, hear the shutter no image saved. The images on the card could still be viewed. The manual states on page 132 that Err blinking is a camera malfunction and to send it in for service. According to the authorized service center in my area the problem was; Err Not Working. Mirror / Box Operation Repaired Aperture Mode / Operation Repaired Checked and cleaned. Replaced part, Aperture Control Unit $32 plus 2.48 tax. $259.48 total cost with labor. I can't say if this is a solution for you, but I was happy to pay for the service, these guys were very old school and I was glad I could support a small shop.

Apple Geniuses actually lied to my niece that a replacement battery would not fix her iPhone 6’s dying battery and she would have to buy a new phone. They told her, they “replaced” her battery with two other replacement batteries and her phone wouldn’t work with the replacements.

So, we bought a replacement battery from iFixit and removed the stripped pentelope screw only to find Apple never removed her original battery. Maybe they merely attached two different batteries to the phone without removing the old battery first or they are actively engaged in deceptive practices.

30 minutes later she replaced her old phone’s battery following this guide and fixed her phone herself. She was ecstatic to see her phone’s battery health back to 100% and proud of her accomplishment. Thank you Walter Galan for a nice simple guide.