GW5_MOST_100.ZIP
GW5_MOST_104.ZIP
GW5_MOST_105.ZIP
GW5_MOST_202.ZIP
GW5_MOST_203.ZIP
GW5_MOST_205.ZIP

The above firmwares are for the MOST based version of the Gateway 500, i.e. Porsche, not the D2B version that is used in Mercedes cars. Installation is as follows:

Extract the G5_B_UPD.ROM file from the update package and copy to the root of an USB flash drive, then connect the USB drive to the Gateway 500 while it is powered. If there is an iPod connected to the Gateway you can leave as it is in any playback mode or status, do not need to disconnect or stop playback.

Update procedure will start automatically within few seconds and takes cca. 1.5 minute. Do not disconnect the USB drive within this time.
After a successful update G5_B_UPD.ROM is deleted from the USB drive and GW.EES.BIN file will appear with the new software version. If an iPod is connected during the update the iPod screen will light for the second time when the upgrade is completed and the new firmware version appears on the right upper corner of the screen.

When finished, it is better to restart the Head Unit and the Gateway 500.