Many parts of the charred scrolls are readable...but those are in vastly better physical shape (comparing "before" & "after") than the few pea-sized cinders remaining of this brain.

Plus - information storage in the brain is both distributed, and micro-scale.

At some point, you are trying to recover compressed data from a HD where only one or two bits can be still read from each 512-byte sector - basic information theory says that the only good-enough tech to do the job would be a time machine.