That was kind of a joke XD. But I looked it up. Ram memory is electricity based, which means it has to be on metal. Ruin couldn't change it once it's loaded. Now, most hard drives (and all SSDs including pen drives) don't need electricity to hold memory. But they're tightly encased on metal. There are some hard drives that use a combination of glass and ceramic for that encasement. I do believe those would be vulnerable when off.
Now, that's not the real issue. Ruin wouldn't need to access the information storage. He can just change the light coming from whichever screen you're looking at the ebook. Again "for anything not set in metal cannot be trusted"