What you have described sounds like the malfunction is being caused by a failed internal component, or software lock up, but, a hard reset may restore operation. Remove the lens, battery and the memory card. Switch the camera to ON and allow it to sit idle for 30 minutes. Switch the camera to OFF and reinstall the battery and card and mount the lens. Try to take a few shots. If the unit does not respond normally, it may require service.
Please keep in mind that my diagnosis & solutions provided are directly dependent on the accuracy of your description of the problem. As with any "do it yourself" fixes, success is a "team effort", since I can't see or touch the camera, and relies on the customer's manual dexterity and ability to follow the instructions well. If the "do it yourself" approach doesn't work out for you and you need conventional repair, please let me know.
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