I wrote the following before I saw Smudgey's reply. Sorry for the reduncancy.

While I was reading your post, I thought you had spilled coffee on the SD card! Now my guess is that the proper card was in the camera, but the lock tab on it prevented writing to it. If one has a dual chip camera, this is another reason to use the second chip for backup, rather than additional storage.

There are Sharpie oil paint pens that are durable and permanent. In my case after I noticed a corner where the point wore off on my Nikon, I purchased a rubber camera body cover from A_z_n. It works very well, except that I enlarged the slot for the front and rear command knobs. I like the stickier grip the cover provides.

This post reminds me of a broader issue regarding setting up a camera. I have a Nikon D810, and have only taken raw photos since I began using a digital camera thirteen years ago. Recently I have used Lightroom starting with version 2 and DxO software. I soon realized that very few of the camera settings other than the basics (shutter speed, F stop, etc.) affect the images imported into this software. I know that Nikon software uses all camera settings as presets, and of course, they are vital if you acquire jpegs. However, they seem to be irrelevant to the software with which I work. They are useful if one wishes to check the image that is captured in what apparently is called "chumming?" ( I never heard of this word being used for this review practice until I joined this forum.) My question is: Why is this fundamental fact not made more evident? I did not see it mentioned in any camera manual, nor in any of the books on the various camera models I have purchased. I even wrote to the authors of two camera books, one on the D7100 the other on the D810, asking the question. Neither author replied. Am I missing something?

I assume your question is "How do I view a Canon raw file on my computer prior to importing it to the raw processing software?" I have used Faststone File Viewer in various versions for at least ten years. It is free for private individuals, and the licensing for commercial use is quite low. I switched from Canon to Nikon four years ago, and it reads raw files in both formats without difficulty. It is very fast. (To check this I deleted its thumbnail cache, then entered a folder with 654 raw images from a Nikon D810, whose raw files range from 71 to 75 MB. It took less than 10 seconds to see all the thumbnails, and there is no perceptible delay to view an image full screen.) The Faststone program has other features, such as the ability to edit and crop JPEGs and TIFFS, as well as rename files. My workflow uses this program initially to select and discard images prior to importing them to my processing software, DxO Photo Lab in my case. I hope this is helpful. I joined the forum three days ago. This is my first post.