It doesn't work like that - a working sharding scheme should not fail if one shard is taken over. This is the most recent description of ethereum sharding if yo

It doesn't work like that - a working sharding scheme should not fail if one shard is taken over. This is the most recent description of ethereum sharding if you want to learn more -> https://youtu.be/9RtSod8EXn4?t=3h12m30s https://youtu.be/9RtSod8EXn4?t=3h12m30s . In particular look at step 4 where the fork choice rule is changed so that shards with invalid blocks cannot exist on a valid base chain.