Some rough notes on getting root and FEL mode on the PCEngine Mini (i couldn't easily find anything online).
Ref:
https://honeylab.hatenablog.jp/entry/2020/03/21/224924 (great work, must read)
Hook up UART pins as documented in the blog above.
screen /dev/ttyUSB0 115200
Power on device spam 's' key on screen console.
Getting root shell via uboot console.
sunxi#setenv init /bin/sh
sunxi#boot
## Booting kernel from Legacy Image at 43800000 ...
Image Name: Linux-3.4.113
Image Type: ARM Linux Kernel Image (uncompressed)
Data Size: 3485072 Bytes = 3.3 MiB
Load Address: 40008000
Entry Point: 40008000
Verifying Checksum ... OK
Loading Kernel Image ... OK
OK
para err in disp_ioctl, cmd = 0xa,screen id = 1
[ 18.397][mmc]: mmc exit start
[ 18.402][mmc]: mmc_config_clock: clk 50000000
[ 18.406][mmc]: mmc_config_clock: clk 400000
[ 18.421][mmc]: mmc 2 cmd 8 err 100
[ 18.427][mmc]: mmc send if cond failed
[ 18.432][mmc]: mmc 2 cmd 55 err 100
[ 18.438][mmc]: send app cmd failed
[ 18.452][mmc]: get sdc_phy_wipe fail.
[ 18.456][mmc]: get sdc0 sdc_erase fail.
[ 18.460][mmc]: get sdc_2xmode ok, val = 1
[ 18.464][mmc]: get sdc_ddrmode ok, val = 1
[ 18.468][mmc]: get sdc_f_max fail,use default 50000000Hz
[ 18.474][mmc]: get card_line ok, card_line = 8
[ 18.478][mmc]: get sdc_ex_dly_used fail,use default
[ 18.483][mmc]: mmc 2 exit ok
[ 18.486]
Starting kernel ...
Uncompressing Linux... done, booting the kernel.
<6/bin/sh: can't access tty; job control turned off
/ # id
uid=0(root) gid=0(root)
/ # passwd
Changing password for root
New password:
Bad password: too short
Retype password:
Password for root changed by root
Power cycle the device, you are good to go, passwd changes are persisted.
/ # �[ 0.203]
U-Boot 2011.09-rc1-00000-g481c142-dirty (Sep 26 2019 - 00:36:30) Allwinner Technology
[ 0.213]version: 1.1.0
[ 0.215]uboot commit : 481c1423f323257356c9db28e780864137596a70
ready
normal dc exist, limit to dc
no key input
dram_para_set start
dram_para_set end
In: Out: Err: Net: Warning: failed to set MAC address
IRQ: EP0
IRQ: EP0
IRQ: EP0
IRQ: EP0
IRQ: EP0
IRQ: EP0
IRQ: EP0
IRQ: EP0
IRQ: EP0
IRQ: EP0
Verifying Checksum ... OK
OK
OK
Uncompressing Linux... done, booting the kernel.
/dev/by-name/UDISK: UUID="beca5410-23bf-4c4a-8702-8d8319d61e01" TYPE="ext4"
/dev/by-name/UDISK already format by ext4
/dev/by-name/rootfs_data: UUID="0de2d00c-f534-419e-b090-368fdb0ae7da" TYPE="ext4"
/dev/by-name/rootfs_data already format by ext4
/dev/by-name/app: UUID="e5969eed-c0e7-40cd-a7fa-972b2ab43660" TYPE="ext4"
/dev/by-name/app already format by ext4
/dev/by-name/misc: UUID="e789e63c-e47f-4f36-8332-b6ef5143cc7d" TYPE="ext4"
/dev/by-name/misc already format by ext4
release-indiana-da99667:INDIANA-mass
Starting logging: OK
Populating /dev using udev: done
read-only file system detected...done
mali: starting driver
mode: 0
automatic mode: display don't support 720p and 480p. 720p mode selected
OK
User Mode:[gpio-keys] Does not verify vid and pid
[joypad-1] device: /dev/input/by-path/platform-sunxi-ehci.1-usb-0:1.2:1.0-event-joystick does not exists.
start game.
start game.
value is: 0
170
Welcome to VividOS
VIVID login: root
Password:
# id
uid=0(root) gid=0(root) groups=0(root),10(wheel)
Spam '2' key while powering up the device via usb.
wopr-re# sunxi-fel -l
USB device 002:034 Allwinner A33 0461872a:89046009:aa96c787:6c118000