Xiaomi Mi WiFi R4 exploration

Have on hands device and some pictures and logs.
Specs like Mi WiFi Router 3G
7621soc with less ram 128 mb, 128 mb nand !!!NO USB!!! and new MI button on top
com connected to usb dongle blocking device to startup :frowning:
if connect after power up works fine with 115200 8n1
Successfully boot initramfs from mi3g.
Failed mtd write kernel, because partitions mismatch ?
Partitions from origin log:

Creating 14 MTD partitions on "MT7621-NAND":
0x000000000000-0x000007f80000 : "ALL"
0x000000000000-0x000000080000 : "Bootloader"
0x000000080000-0x0000000c0000 : "Config"
0x0000000c0000-0x000000100000 : "Bdata"
0x000000100000-0x000000140000 : "Factory"
0x000000140000-0x000000180000 : "crash"
0x000000180000-0x0000001c0000 : "crash_syslog"
0x0000001c0000-0x000000200000 : "cfg_bak"
0x000000200000-0x000000600000 : "kernel0"
0x000000600000-0x000000a00000 : "kernel1"
0x000000a00000-0x000002400000 : "rootfs0"
0x000002400000-0x000003e00000 : "rootfs1"
0x000003e00000-0x000006400000 : "overlay"
0x000006400000-0x000007f80000 : "obr"

Photos:
Case
Front
Back
SOC
WIFI
Ports
Original LOG
For now i am bricked it :frowning: with flashing u-boot from jwangac
Need help with how to switch SOC from NAND flash to SPI flash. Аnd how to build uboot for it.
I have backup of original uboot binary.
found on MTK7621 Datasheet control pins for selecting nand or spi chip on page 21:
{RTS2_N, RTS3_N, TXD1, GPIO0}
have w25q128fv free chips, datasheet page 86 shows it have 4-byte qpi adressing.

RTS2_N, ball J3
RTS3_N, ball J4
TXD1, ball R14
GPIO0, ball P12

PIN ND_CS_N, ball G2, SPI_CS0, SPI chip select 0

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I also with my router in "brick", can you tell me how to return the original firmware? Alguem pode me ajudar a voltar o firmware original?

any updates, very hard to find out soc pinout :frowning: switch SOC from NAND flash to SPI flash.

-- update --

Install uboot breed for easy recovery

Openwrt is now available for both 4A and 4Q both of which were released after R4. Can someone care to explain why not this device?