Ok. I will give that a shot. Can you list the steps/reformatting procedure?
You need a computer with an SD card slot. Simply format it with the computer. It doesn't really matter what file format to use, since the Roku will re-format it. but the computer format will find any bad sectors and mark them as unusable. That's usually what happens with SD cards, they get a bad sector and data gets corrupted.
Once you've done the computer format, put the card back in the Roku. It will ask to format the card, and say yes.
Dan Roku Stick (3600), Ultra (4640), Ultra (4670), Premiere (3920), Insignia 720p Roku TV, Sharp 4K Roku TV, Nvidia Shield, Windows 10 Pro x64 running Serviio and Plex on a wired Gigabit network.
We are having a problem that the Sharp Roku tv seems to be power cycling. the input light blinks, it says "Sharp Roku" on the screen for a second or 2, then goes dark, the power indicator light blinks again, over and over. We have not put and SD card in the TV ever, I don't even see a slot for one.