Help - Why no serial console output after "Starting kernel..."?

U-Boot 2013.10-tld-4 (Sep 08 2014 - 19:43:38) for OXNAS

DRAM:  128 MiB
NAND:  128 MiB
In:    serial
Out:   serial
Err:   serial
Net:
Led:    GREEN
mii0
Main Loop
Waiting for PHY auto negotiation to complete.... TIMEOUT!
ENET Speed is 10 Mbps - HALF duplex connection
Using mii0 device
ping failed; host 192.168.100.160 is not alive
Hit any key to stop autoboot:  0
OX820> printenv
autoload=no
baudrate=115200
bootargs=console=ttyS0,115200n8
bootcmd=run dt_bootcmd_usb
bootdelay=10
console=console=ttyS0,115200n8
dt_bootcmd_usb=usb start; run dt_usb_bootcmd; usb stop; reset
dt_bootm=bootm $uimage_addr $uinitrd_addr $dtb_addr
dt_load_dtb=ext2load usb 0:1 $dtb_addr $fdt_file
dt_load_initrd=ext2load usb 0:1 $uinitrd_addr /boot/uInitrd
dt_load_uimage=ext2load usb 0:1 $uimage_addr /boot/uImage
dt_usb_boot=run dt_load_uimage; run dt_load_initrd; run dt_load_dtb; run dt_bootm
dt_usb_bootcmd=run usb_set_bootargs; run dt_usb_boot
dtb_addr=0x62c00000
ethact=mii0
ethaddr=00:25:31:02:xx:xx
fdt_file=/boot/dts/ox820-pogoplug-pro.dtb
if_netconsole=ping $serverip
ipaddr=192.168.100.10
mtdids=nand0=41000000.nand
mtdparts=mtdparts=41000000.nand:14m(boot),-(data)
preboot=run preboot_nc
preboot_nc=run if_netconsole start_netconsole
serverip=192.168.100.160
setenv=fdt_file /boot/dts/ox820-pogoplug-classic.dtb
start_netconsole=setenv ncip $serverip; setenv bootdelay 10; setenv stdin nc; setenv stdout nc; setenv stderr nc; version
stderr=serial
stdin=serial
stdout=serial
uimage_addr=0x60500000
uinitrd_addr=0x60e00000
usb_device=0:1
usb_set_bootargs=setenv bootargs console=ttyS0,115200 root=/dev/sda1 rootdelay=10

Environment size: 1296/131068 bytes
OX820> boot
(Re)start USB...
USB0:   USB EHCI 1.00
scanning bus 0 for devices... 3 USB Device(s) found
       scanning usb for storage devices... 1 Storage Device(s) found
4170064 bytes read in 455 ms (8.7 MiB/s)
1975075 bytes read in 345 ms (5.5 MiB/s)
7029 bytes read in 237 ms (28.3 KiB/s)
## Booting kernel from Legacy Image at 60500000 ...
   Image Name:   Linux-3.18.5-oxnas-tld-1
   Created:      2015-04-08   3:59:57 UTC
   Image Type:   ARM Linux Kernel Image (uncompressed)
   Data Size:    4170000 Bytes = 4 MiB
   Load Address: 60008000
   Entry Point:  60008000
   Verifying Checksum ... OK
## Loading init Ramdisk from Legacy Image at 60e00000 ...
   Image Name:   initramfs-3.18.5-oxnas-tld-1
   Created:      2015-04-08   4:00:00 UTC
   Image Type:   ARM Linux RAMDisk Image (gzip compressed)
   Data Size:    1975011 Bytes = 1.9 MiB
   Load Address: 60000000
   Entry Point:  60000000
   Verifying Checksum ... OK
## Flattened Device Tree blob at 62c00000
   Booting using the fdt blob at 0x62c00000
   Loading Kernel Image ... OK
   Loading Ramdisk to 67c46000, end 67e282e3 ... OK
   Loading Device Tree to 67c41000, end 67c45b74 ... OK

Led:    GREEN

Starting kernel ...

Uncompressing Linux... done, booting the kernel.

fdt_file=/boot/dts/ox820-pogoplug-pro.dtb
setenv=fdt_file /boot/dts/ox820-pogoplug-classic.dtb