APX Mode (USB Recovery Mode "RCM")

APX Mode (NVIDIA USB Recovery Mode) can be used to run Fusee Gelee or to use Nvidia tools to flash the hardware.

Entering APX Mode

Note - you will need a USB3 port on your development computer.
Power off the SurfaceRT or RT2 (not sleep mode!) When the device is shut off, plug in a USB type A into the Surface, and a USB type A (or type C depending on your development device) into your development computer. Hold VOL-UP; Press PWR and release it. Release VOL-UP if dmesg -Tw shows:
Surface RT
Once connected in APX mode, you can use NVidia tools or a precompiled Fusee Gelee on your device. Nvflash v2.6 - NvFlash tool for getting uid -

Entering APX Mode from anywhere

Connect USB - A-to-A cable Write 0x00000002 to 0x7000E450 <- sets bit in PMC-register to indicate to boot to RCM Write 0x00000010 to 0x7000E400 <- reboot This should force reset in RCM Mode

Enter RCM from UEFI Shell

Boot UEFI Shell as normal. use this startup.nsh
### Blink screen to indicate the the script has started
mm 0x7000A000 0x8010000E -w 4
stall 1000000
mm 0x7000A000 0x80FF000E -w 4
stall 10000000 # waits 10s; plug in the usb a-a cable in this time
# reboot to RCM is usb a-a cable is connected
mm 0x7000E450 0x02 -w 4 # Write RCM bit
mm 0x7000E400 0x10 -w 4 # reset