I've never checked it, but I'm sure that this is what a Bios Loader should do. I know that you use the Bios Loader to run all the homebrew stuff on your xbox without the need of opening it. To flash the Onboardchip you need to solder a wire and so you would have to open the xbox. That would mean that the Bios Loader couldn't be used to run homebrew apps on your xbox without opening and that stays in contrast to all I know. There is the Webpage of the Loader This is from the readme ==============
For the first time ever, we have made it possible to boot a completely new rom
from the hard drive, when booting from ANY kernel
You will need to provide your own bios and RC4 key as those are illegal to
distribute without permission from Microsoft.
We have given a prerelease of our new version to a couple of other groups
and they have told us that the following bioses work (not all may be
available currently but we have been told they will be soon).
Currently known working bioses:
- Retail 3944 BFM
- Retail 4034 BFM
- Retail 4817 BFM
- Retail 5101 BFM
- *Complex Debug Bios BFM
- *Complex Evoxdash Debug Bios BFM
- Evox V2.6 BFM
- Evox V2.6 EjectFix BFM
- Evox D.6 BFM
- Evox D.6 EjectFix BFM
- X2 4976.02 BFM
- X2 4977 BFM
- *5455 Debug
- *5558 Debug
(* Debug bioses expect the XDK Launcher to be properly installed.)
Step 1 - Install files Install the included default.xbe, phoenix.raw,
and boot.cfg file into the directory of your choice on your
xbox, using any method you prefer (007 hack, dash hack, evox).
Install any bios(es) you wish to load into the same directory.
To get started, just rename the one you want to load to
"xboxrom.bin". Don't forget to sign the default.xbe for the boot
method you are using.
Step 2 - Edit boot.cfg
Step 2a- Edit the RC4Key entry to be the appropriate RC4 key for the bios
you are loading. If you specify the key to be all 0x00's, it will
assume the 2BL is decrypted already in the rom you are providing.
Also note that if you really want to rename your bios file, you
can provide the name here with the Romfile parameter.
Step 2b- Specify a second rom to boot when tray is open (this is optional).
Edit the AltRomfile entry to be the name of a second rom you would
like to boot if you run the loader with the tray open.
If you comment out the AltRomfile line, the loader will always try to
load the rom specified with the Romfile entry.
Step 2c- Edit the EEPROMKey1_0 and EEPROMKey1_1 entries. You only really need
to put in the one for your version of the Xbox. Now at runtime the
loader will detect your xbox version and patch in the appropriate
EEPROM key. Hopefully this will help out the save game problem too.
We would have liked to have provided the keys, but we decided against
it for legal reasons.
DO NOT JUST COPY IN THE NEW XBE WITHOUT ADDING THE EEPROM KEYS TO THE BOOT.CFG
Step 2d- Edit the LEDSequence to your liking. You can use the letter r, o,
g, and x here to represent red, orange, green, and off, respectivly.
So, for example:
LEDSequence oxxx would be slow orange flash
LEDSequence rrgg would be slow red/green flash
LEDSequence rogo would be all crazy like
LEDSequence gggg would be solid green
If you comment out the LEDSequence line the LED's will not be modified
by the loader.
Step 2e- Set the Debug parameter to your liking.
"Debug true" Will cause the intro/splash to not be displayed, and
cause detailed debugging messages to be displayed. (case sensitive)
Any other value will cause normal behavior.
Step 3 - Launch the application. Depending on your preference you may be
launching the application via the dash hack, or the 007 hack, or
the audio hack, or from any 3rd party dashboard. Just go ahead
and launch our app! You will see our intro being rendered (don't
worry, it will only display the full intro the first time you run
it), and then you will find yourself in whatever dash the bios
normally will launch. If you have setup a secondary bios (as
specified in Step 2b) you can load that bios by ejecting the tray
and leaving it open when you run our loader. Note that if you are
launching the application automatically from the dash hack, you will
need to be careful as you could find yourself in an infinite loop if
you are loading a bios which tries to boot the Microsoft dashboard.
Various bioses look for evoxdash.xbe first, so as long as you are
using one of those bioses and you have evoxdash.xbe installed, it
will launch that one first.