SLUUCD5 January 2023 BQ27427
UNSEALED Access: This byte contains the checksum on the 32 bytes of block data read or written. The least-significant byte of the sum of the data bytes written must be complemented ([255 – x], for x the least-significant byte) before being written to 0x60. For a block write, the correct complemented checksum must be written before the BlockData() will be transferred to RAM.
SEALED Access: This command is not available in SEALED mode.