It seems to be a mistake on some of the xenoFX with red color PCB regarding a flash type bridge on the PCB. The PCB is configured for SST49LF020A but the flash is SST49LF002B.
In order to write enable the flash in this case you need to move a solder bridge as showed on the image below. There could be a small resistor on the PCB instead of solder, but it is zero Ohm, so just make a solder bridge as showed on the image above (or move the resistor).
* CAUTION! * Make sure you don’t bridge all three solder pads as it will short out the xbox, power straight to ground!