I managed to unbrick the device by restoring the original (vendor's) copy of u-boot in NAND. This is how: Prepare bootable SATA disk with kref's SPL + u-boot. Before compiling, change the frequecy from 800MHz to 750MHz in include/configs/ox820.h. Do not bother about the kernel and rootfs, just SPL, and u-boot.img on the FAT partition. Network does not work [*], but we can get away wiby crosser - uBoot
WarheadsSE, can you point me to the source from which the stage1 images in oxnas_sata_boot tar are built? Then I could try to play with timeings etc. I've got the source of u-boot from the vendor (Shuttle). That one is guaranteed to contain working config, I could try to find it there. (Although so far I cannot identify stage1 sources in the vendor's tar.) I tried to use u-bootby crosser - uBoot
I have Shuttle Omninas kd20, and I managed to screw its u-boot image in NAND. So it does not boot into u-boot from NAND anymore. The board does have serial header (which I am using), but no JTAG header. And obviously it has 2 SATA interfaces (it's a NAS box). I am trying to use this guide to boot from SATA disk, and it works. Almost. First, using different stage1 images result in reportedby crosser - uBoot