delete the blocks and chainstate folders and restart bitcoind.
It restarted from the first block already, but i'm trying this one more time.
@darosior I changed ownership to `pi` and chmod-ed the hard drive mount. Does bitcoind use a specific user that I need to change to?
Also, note that I didn't specify a path to save the block chain to bitcoind - instead, the folder .bitcoin links to my drive.
`bitcoind` uses a specific user only if you specify it (for instance in a systemd service).