At the end, before my printer stopped displaying files on the control panel, I had to re-save files on to the SD card to make them appear on the control panel. The panel would show no files, I would re-save the file on my computer, then re-inset the SD card and the file would appear. After several days, this didn't work and no files appeared on the control panel. I changed cards, re-formatted the SD cards, changed slicers, turned off the machine, re-started but no files appear on the control panel.
Any suggestions on how to fix my problems? By the way, this happened 10 days after the warranty expired - the 30 day warranty Amazon provides.
Thanks.