Updating firmware L3+ error. "cannot find signature"

when trying to upgrade L3+ firmware to BlissZ or AsicFW.io firmware I get the same error. Found a work around on bitcointalk but i’m not super savvy with command prompts. trying to use MAC terminal, but don’t know how.

link → How to bypass ""Cannot find Signature" when updating your antminer firmware.

anyone help?

Or anyone else run into this problem and have a solution?