I have an elderly friend that uses a 6D same as I do. Her camera is probably 3 years older than my camera. We often go out together to take pictures of different things depending on the season. We also share lenses. Her camera does the following; 1. The little red light that comes on after taking several pictures stays on for ever, something in order of 15-20 seconds. 2. Looking at our pictures taken of the same scene with the same 50 f/1.8 STM lens and same camera settings her images sometimes looks under exposed. 3. After taking a picture using her Lexar SD card we can view the images on the back of the camera but not on her laptop or my home computer. I've loaned her a SanDisk SD card and that may have resolved the problem. I also want to mention that she recently purchased a cheap eBay battery grip and that came with 2 batteries. Could these items cause any problems. She cant afford to send it off right now but I told her she can pay me back later so off it goes to Canon in Virginia tomorrow. Thanks for your response!