Trying a new/known-good SD card sounds like a good idea to me. I think there's a good chance that will resolve the issue.
But if it doesn't, then there's probably some sort of hardware issue with your 700, and there's not much that can be done about that. Sometimes old stuff breaks, and it's not always practical to repair. Try getting Dell or HP to fix a 12-yr-old laptop with a bad motherboard. They might do it, but for the cost, it just wouldn't make sense.