Have you tried turning the camera on with the memory card removed? If not, please do so, and if it powers up please let me know. If not, try a hard reset below:
Remove the battery, memory card and lens (use the body cap to protect the mirror area). Switch the camera ON. Allow it to sit idle for 1 hour. Switch the camera off. Insert the battery, memory card and remount the lens and try it out. If normal operation is not restored then the main circuit board has a faulty component in the power supply section and the camera will require professional 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 you require additional information, please use the Reply to Expert Tab to contact me. Click the ratings only after our exchange is complete and you are satisfied.
If you are satisfied that my answer is accurate, please do not forget to rate my answer OK, Good or Excellent.