Reflash Yun: Loading: *len bad 46 < 56, Bad Magic Number

I’m trying to reflash a Yun’s kernel.

  • Ethernet cable is plugged in.
  • YunSerialTerminal sketch is loaded.
  • The TFTP server is confirmed working and the file locations are correct.

When I try to flash, it says:

Using eth0 device
TFTP from server; our IP address is
Filename '1.5.3/openwrt-ar71xx-generic-yun-16M-kernel.bin'.
Load address: 0x80060000
Loading: *len bad 46 < 56
T T T T T T T T T T 
Retry count exceeded; starting again

This device fails to boot on its own. When I press YUN RST, it gives:

U-Boot 1.1.4-dirty (Nov 13 2014 - 18:54:12)

Arduino Yun (ar9331) U-boot

DRAM:  64 MB
Top of RAM usable for U-Boot at: 84000000
Reserving 142k for U-Boot at: 83fdc000
Reserving 192k for malloc() at: 83fac000
Reserving 44 Bytes for Board Info at: 83fabfd4
Reserving 36 Bytes for Global Data at: 83fabfb0
Reserving 128k for boot params() at: 83f8bfb0
Stack Pointer at: 83f8bf98
Now running in RAM - U-Boot at: 83fdc000
Flash Manuf Id 0xef, DeviceId0 0x40, DeviceId1 0x18
flash size 16777216, sector count = 256
Flash: 16 MB
Using default environment

In:    serial
Out:   serial
Err:   serial
Net:   ag7240_enet_initialize...
No valid address in Flash. Using fixed address
No valid address in Flash. Using fixed address
: cfg1 0x5 cfg2 0x7114
eth0: 00:03:7f:09:0b:ad
eth0 up
: cfg1 0xf cfg2 0x7214
eth1: 00:03:7f:09:0b:ad
ATHRS26: resetting s26
ATHRS26: s26 reset done
eth1 up
eth0, eth1
autoboot in 4 seconds (type 'ard' to enter u-boot console)...
## Booting image at 9fea0000 ...
Bad Magic Number

Is this device bricked, or is there something I can try?