If no chips are harmed and luckily no MFT files on the plate is missing then the chance of reading something nasty might be close to zero - if the attacker has

If no chips are harmed and luckily no MFT files on the plate is missing then the chance of reading something nasty might be close to zero - if the attacker has some HDD restoring skills. But usually people with this kind of skill have a better use of their time by earning a lot of money and if regular attacker uses HDD restoring service then he has to pay a lot of money to serviceman which seems not worth of it. So, you did a good job if destroying a working thing might be considered as something good.