Stuck in recovery mode

I recently updated my mid 2010 iMac from Snow Leopard to El Capitan. I then booted into internet recovery mode and erased my hard drive as I want to sell this computer, but now I can't get out of internet recovery mode? Whether I restart, shut down, or turn it off and on with the power button it keeps booting back into internet recovery mode. I have tried resetting NVRAM but nothing happens (I don't hear the turning on sound twice). I have also tried holding option at startup and only Recovery comes up as an available option to boot with.