I was near the end of downloading the blockchain data or blk??.dat when it started getting "warning 52 of last 100 blocks have unexpected version". I don't know what to do at this point!  I was able to figure out that when my 256GB SanDisk card got full, it was able to restart when I -prune=550 !  When I did the prune the 1st time, it started at 2019 for redo the blockchain! Maybe when I do a GUI, I'll do it next time when the blockchain gets full again on 2nd Raspberry Pi 4!  I keep looking for commands that would eliminate "warning 52 of last 100 blocks have unexpected version" so finish the blockchain download or go to GUI to finish downloading the Bitcoin blockchain.  I might get a 512GB SanDisk next time that'll cover the blockchain data.  200GB is not really enough for Bitcoin blockchain data anymore!