#1 using Jtag, nothing else will matter, and even then it will only work until your drive is reflashed again in another attack. Best way to secure HDD would be modifying firmware to DISABLE firmware upgrades and external access to service area permanently. Afaik HDDs keep some executable modules stored on HDD platters, that means 'simply' cutting WR leg on eprom chip is not enough. We are talking quite significant firmware rewrite here.