Convert OpenGL app to OpenGL ES

I have a game written in C that runs using OpenGL. I want to convert that game into an OpenGL ES app that plays on Android via the NDK--in C code, basically. Currently I have done some of the porting--I can get the sound, the touchscreen, and the accelerometer to work--but I am not able to draw anything correctly. There are not that many lines of code which require conversion. I do not estimate more than 15 hours of work.