Not sure what would cause the white screen - I haven't run into that issue in quite some time.
As for getting back to the calibration, you can navigate the entire menu structure using the tuner knob. After you power on, briefly press in the knob, then rotate until the gear is selected, then press the knob again. Press the knob again to select the calibration submenu. Finally, turn the knob to select touch screen, and press the knob button to re-enter calibration.
Side note: I didn't intentionally change the calibration storage location, so I'm a bit surprised it would need recalibration after updating.
HOWEVER, I just tried walking through the touch calibration procedure, and it appears that I've accidentally broken it somehow, so I'll try and fix that tonight, since it is a pretty important function.