Update XboxHD+ to firmware 2.2.2 with a patched M8+ BIOS

Introduction

XboxHD+ boards bought from AliExpress often ship with firmware older than 2.2.2. Cerbios needs at least 2.2.2, so the board has to be updated first. The update runs on the Xbox with the firmware program firmware.xbe, and it needs an Evox M8+ BIOS patched with the XboxHD+ kernel patch (m8plus_kpatcher.ips).

We wrote this guide because we got no video with Cerbios and an XboxHD+ on older firmware. With firmware 2.2.2, Cerbios 2.4.2 works.

What you need

An Xbox with a modchip that takes a 256 KB BIOS (e.g. OpenXenium), and a way to recover if something goes wrong (e.g. booting from TSOP or another bank).
A dashboard, e.g. UIX Lite, and FTP access to C:.
XboxHD+ firmware 2.2.2 from xbins. The easiest way to get it is with Pandora V2. Support for Apple silicon Macs is in pull request #5, which isn't merged yet.
Evox M8+ BIOS: M8plus.bin for Xbox 1.0–1.5 or M8plus_16.bin for 1.6.
m8plus_kpatcher.ips from MakeMHz.
evtool-rs by Swedish developer billy (@ohgrenbilly on X). Ready-made builds for Mac, Linux and Windows are under Releases.

1. Pick the right BIOS

Xbox version	BIOS
1.0–1.5	`M8plus.bin`
1.6	`M8plus_16.bin`

A _16 BIOS won't work on 1.0–1.5, and the other way around. The patch works on every M8+ release except those patched for forced 480p.

2. Patch the BIOS

On a 1.6, replace M8plus.bin with M8plus_16.bin:

evtool-rs unpack M8plus.bin xboxkrnl.img
evtool-rs ips    xboxkrnl.img m8plus_kpatcher.ips xboxkrnl_kpatched.img
evtool-rs pack   xboxkrnl_kpatched.img M8plus.bin M8plus_kpatched.bin

Don't change the dashboard path. The BIOS should boot your usual dashboard.

3. Copy the files to the Xbox

Unzip the firmware. Copy the whole xboxhd folder to C: over FTP, so you end up with C:\xboxhd\. The folder must be exactly there, because the patched kernel reads C:\xboxhd\kp.bin.

4. Flash and update

Flash M8plus_kpatched.bin to the modchip.
Boot from the modchip. The Xbox starts your dashboard as usual.
Go to C:\xboxhd\ and start firmware.xbe. The folder also has a default.xbe, but it may complain about your video settings. Use firmware.xbe.
A message says the update starts in two minutes. Wait. Don't turn off the Xbox while it flashes.
When the flash is done, the Xbox turns itself off.

5. Install Cerbios

Once the XboxHD+ has firmware 2.2.2, you can flash Cerbios 2.4.2 instead of the patched M8+ BIOS. You can delete C:\xboxhd\ afterwards.

Cerbios 3.1 and later need the XboxHD+ flashed with the new XboxHDMI-TR firmware. We'll cover that in a separate guide.

Troubleshooting

Black screen right at boot: check that you used the right BIOS for your Xbox version (step 1).
default.xbe complains about video settings: start firmware.xbe instead.
Nothing happens after starting firmware.xbe: wait at least two minutes before doing anything.