You can't reform a bigoted, corrupted soul with a little extra training. Even if you replace every single sentence old officers say to their cadets in the academy, the culture will pervade between training and those who resist it will be run out of the system.

The only choices we have are either keep the police as they are, but reduce their numbers by at least 90% so they can respond to the 3% of calls that are actually violent. We keep them violent bastards, but only unleash them on other violent people, like human attack dogs.

Or, abolish them entirely and rebuild an entirely new peace-keeping force with absolutely no members of the previous force involved at all, a completely fresh start like what Georgia did. One of the major problems with police culture is the unbroken lineage of old officers training new cadets dating back to their days as slave patrols and union busters (which is how the police got the idea for the police union - beating up union workers). If you sever that lineage, you sever the old, old, old attitudes that it kept alive within the police.