[U-Boot] key combination in Xburst mini laptop

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 co

[U-Boot] U-boot bootcmd

Hello everybody ! I got recently one of Xburst based mini laptops ( Skytex SX E700) running version of Linux that I don't like. No support anymore so no info about how to start upgrade process or to boot from SD/USB. Info for similar laptops does not work. U-boot shell shows that I have 3 boot var