RecalBox boot from a USB on a Raspberry Pi 3

RecalBox boot from a USB on a Raspberry Pi 3

So you finally figured out to boot your Raspberry Pi 3 to a USB without an SD card inserted.
See:
https://www.raspberrypi.org/documentation/hardware/raspberrypi/bootmodes/msd.md

Note: There are consequences.
See:
https://www.raspberrypi.org/blog/pi-3-booting-part-i-usb-mass-storage-boot/

Also note that booting from a USB stick will be slower than booting from a SD card. But in some cases, the convenience outweighs the longer boot time and slower data access.
In general, SD cards are, by design, faster than usb sticks and I believe I read that the Pi usb shares a data bus with the ethernet port.

So you have installed a RecalBox on a bootable Pi USB stick and it will not boot.
https://www.recalbox.com/

The fix for me was editing the cmdline.txt file.
Orig:
dwc_otg.fiq_fix_enable=1 sdhci-bcm2708.sync_after_dma=0 dwc_otg.lpm_enable=0 console=tty3 consoleblank=0 loglevel=3 elevator=deadline vt.global_cursor_default=0 logo.nologo root=/dev/mmcblk0p2 rootwait fastboot noswap ro
New:
dwc_otg.fiq_fix_enable=1 sdhci-bcm2708.sync_after_dma=0 dwc_otg.lpm_enable=0 console=tty3 consoleblank=0 loglevel=3 elevator=deadline vt.global_cursor_default=0 logo.nologo root=/dev/sda1 rootwait fastboot noswap ro

So changing:
root=/dev/mmcblk0p2
to
root=/dev/sda1

Update: root=/dev/sda2 on the newest one!