you may have to dump some of your own games depending on if the keystone is available. not difficult, but it can take up to a couple of hours to do all steps. if the keystone is not available, your legit saves will come up as corrupted. that's one thing that's a pita about the exploits.
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the only thing that might happen is a kernel panic where the system shuts off. it's a race attack exploit like the wii u's early exploits, but it can cause that to happen. that's the only thing I can think of that's actually bad. some people have mentioned it corrupted their hard drives, but that's not happened to me.