“Fixing small missing pieces of brain” should work anyway with replacing a chip and apply usual learning technique to have the chip re-integrate lost functionality.
Anyway this problem, of being able to replace a broken chip, is secondary to making the chip behaving like a piece of brain tissue.
Which may begin with how a relatively uniform structure connected “anarchically” in both X-Y directions could be morphed into a hierarchical one as in mini columns or columns. I assume most connections of any layer are with neurons from a following layer, with some fewer connections ( if any?) within same layer, then some distant lateral connections.
One way to approach this could be - if technology permits - to have the fibers placed not entirely random but with some directional prefference over e.g. vertical axis of the grid. Statistically to have fewer horizontal fibers, a bit more at an angle and most of them vertical.
Another approach could by to electrically fry most lateral connections between contacts on the same row. Again there-s a feasability question mark here too.