If it's the version 3.0 PanelDue board, then the only way I can think of is to flash it with the wrong size firmware (e.g. the 5" firmware), start it up (which will cause it to delete the touch calibration when it detects the screen size change), then flash it with the correct firmware.
Problem has been solved. The problem was me. I did not have 3 check boxes checked in Bossa 1.8 that needed to be checked. I went back and re-read the instructions on DC42's blog and fixed my error. My PanelDue is now updated.
It looks to me that the RADDS build of RRF is set up to support 2 SD cards. However, the same card detect pin seem to have been used for both of them. I don't know whether anyone has tried to use the SD card slot on PanelDue with RADDS.
@dc42
ok, I'll try that monday... I generally use a fingernail, but when have to use the screen more, as seen, I use a piece of filament with the tip melted into a rounded blob š