The 700 is getting pretty long in the tooth, and unfortunately display calibration issues tend to grow over time. The "leave it on overnight face down" trick is worth trying, but is not a guaranteed solution.
If you cannot get the screen to calibrate, then you have only two options: Send the unit in to AP for a screen replacement, or replace the unit. Due to the age of the 700 and the cost of a screen replacement, I would not recommend that option. With the ability to run iFly on a tablet so that the device can be used for other purposes besides flying, unless you absolutely need the sunlight-readable display, I would recommend the tablet approach, but the current 740b is a very good option if you need the sunlight-readability. The display is much brighter than the 700, and the calibration issue is much less likely to occur (I don't think I've ever heard anyone with display calibration issues on a 740 or 740b).
Not sure what you mean by "new updated SD card from iFly". If you did that for an operating system / firmware upgrade, there may be some relationship to your calibration because I think the calibration may be reset to defaults during that process. If you did that just to get the latest iFly application software, then there would be no connection.