The proper way to secure erase a SSD is to issue the SECURITY ERASE UNIT command. Then the SSD controller should send a BLOCK ERASE command to all physical blocks.
One caveat: the SSD has to be connected directly to the SATA interface. Don't use a SATA-to-USB adapter!
Since we cannot plug an USB pen drive into a SATA port, what is the proper way to secure erase a USB pen drive and restore its factory default state?
This will not do the trick:
$ sudo hdparm --security-set-pass PASS /dev/sdb $ sudo hdparm --security-erase PASS /dev/sdb
Before marking this question as a duplicate: most duplicates are closed and suggest to
dd everything several times, but that won't restore the factory default state.