I have the same problem and this is what i did to fix it. It is almost like a hard reboot from scratch. First, pop the back cover and remove 9 screws from the back. Once the 9 screws are removed, use a small flat head screw driver to pry open the cover. Once the cover is open, disconnect two ribbon cables, one big one small, and put back the cover without the ribbons being connect. Now press and hold the power button until the main screen go away so it will drain all the power being stored. Now when that is done you can reconnect the two ribbon cables and put back the cover. Now try press and hold down the power button and it will initialize from scratch. I think it has about 97 files to load up. This should fix the sim card not being detected. Hope this help….