[U-Boot] key combination in Xburst mini laptop

[Boris Borisov]

Hello everybody!

My mini laptop toy has three variables set in u-boot shell : bootcmd,
bootcmd_sd and bootcmd_sd_nerase. Is there way to see which key
combination is used to branch the boot process. I want to boot from
SD/USB to alter the default Linux install. Brand name Skytex SX E700.
No key combo known from others similar devices seems to work.

Thanks