Let's say we have 100 blocks. A miner x intends to manipulate block 90. Therefore, he must recalculate the hash for block 90. Subsequently, he must also recalculate the hash values for block 91-100.
Correct me if I speak pointlessly here.
So how can all the other miners discover that the miner is cheating x? And what happens to Bergmann x if he gets caught?