You flashed what, HP bios file… it doesn’t matter, bios update files/downgrades/upgrades doesnt fix ME Firmware engine corruption, the pointed guide is to be done by the user and only on the user side, read it learn it and fix, there’s thousands of user reports of sucessful “fix’s”…
This is not an easy task for unexperienced/1rs time users that never done it or knows how to recover systems so, a capable tech it repair shop will be the best option for this.
Sorry but there’s things that are to too much time-consumming or that cant be remotely fixed by posts in a forum.
Your system uses ME v6 Ignition IBX, files needed to complement the guide operations are here:
Intel (Conv.Sec.) Management Engine: Drivers, Firmware and Tools (2-15) - Special Topics / Intel Management Engine - Win-Raid Forum
This assuming that using ME jumper, allows write operations, last resource an IC SPI programmer and full image programming, still with clean ME FW region.
Several threads on the forum on Z2xx machines bios recover and ME v6 IBX re-initialization.
An example: HP Z200 Small Form Factor Workstation - Management platform in manufacturing mode/shuts down after 30 minutes - Special Topics / Intel Management Engine - Win-Raid Forum
Nothing more to add, good luck.