Sorry for late reply. I managed to fix my board and flash LEDE snapshot on it, you can follow below instruction:
Make sure you have selected booting from firmware A in vendor GUI
By default, vendor GUI should be available on 192.168.11.1 (login/password: admin/admin).
On serial console, during early stage of booting process (U-Boot) you should see something like below (important lines: "Current Image was A" and "## Booting image at 9fd50000"):
[...]
[eapsw_watchdog::status] cold start
[eapsw_watchdog::status] boot normally
[eapsw_watchdog::status] autoswitch enabled=On , times=None
Current Image was A
In: serial
Out: serial
Err: serial
Net: ag934x_enet_initialize...
[...]
## Booting image at 9fd50000 ...
Image Name: Linux Kernel Image
Created: 2014-10-14 3:25:40 UTC
Image Type: MIPS Linux Kernel Image (lzma compressed)
Data Size: 927620 Bytes = 905.9 kB
Load Address: 80002000
Entry Point: 801edab0
Verifying Checksum at 0x81000040 ...OK
Uncompressing Kernel Image ...
[...]
Download and flash LEDE image from TFTP server
- Check TFTP IP server in U-Boot with:
printenv serverip
command (on my board it's 192.168.100.11).
- Setup TFTP server on your PC (with static IP from previous point, 192.168.100.11/24 in my case).
- Make image lede-ar71xx-generic-alfa-ap120c-squashfs-sysupgrade.bin available to download from configured TFTP server.
- Interrupt booting process in U-Boot and issue below commands:
tftp 0x80060000 lede-ar71xx-generic-alfa-ap120c-squashfs-sysupgrade.bin
erase 0x9f050000 +0xe80000
cp.b 0x80060000 0x9f050000 $filesize
reset
Example output from a successful update:
EAP9112A> tftp 0x80060000 lede-ar71xx-generic-alfa-ap120c-squashfs-sysupgrade.bin
Trying eth0
Using eth0 device
TFTP from server 192.168.100.11; our IP address is 192.168.100.46
Filename 'lede-ar71xx-generic-alfa-ap120c-squashfs-sysupgrade.bin'.
Load address: 0x80060000
Loading: *#################################################################
#################################################################
[...]
#####
done
Bytes transferred = 15001125 (e4e625 hex)
EAP9112A> erase 0x9f050000 +0xe80000
Erase Flash from 0x9f050000 to 0x9fecffff in Bank # 1 erase flash#0
First 0x5 last 0xec sector size 0x10000
Erased 232 sectors
EAP9112A> cp.b 0x80060000 0x9f050000 $filesize
Copy to Flash... write flash#0
write addr: 50000
done
EAP9112A> reset
Resetting...
And that's all, if everything goes well, you should have LEDE on board 