Mac boot ROM virus is real

WARNING:

If you are of the school that macs can't get viruses (despite Apple's security updates designed to protect against them) and do not wish to be disillusioned (yet...), please skip this post. For those of you on the frontlines: has ANYONE successfully overwritten the boot rom? Via a USB port, my computer was infected. A wipe with 7 pass zeroing and internet-only reinstall fails to erase virus, revealing that it is indeed at the boot rom level. Apple security updates and El Capitan securities, designed to protect EFI vulnerabilities, can supposedly close this barn door but, in my case, the horse has already escaped. My next step is trashing this now-bricked machine and repurchasing. I'd love to hear from anyone who has encountered this and has a boot rom fix or can do some brainstorming!

Recap: erased with 7-pass. Re-partioned. Clean, internet-only install (no peripherals). Security updates, upgraded to El Capitan. Hijacks persist.

<Edited By Host>