Hi,

Unfortunately my Sonos Connect AMP got bricked somehow. I opened it up, measured the voltages and found a UART port. I hooked it up to my laptop and it gave me the following serial output:
 

U-Boot 1.1.1(1-17-3-2.1), Build: 2.1

MPC8272 Reset Status: Check Stop, External Soft, External Hard

MPC8272 Clock Configuration
 - Bus-to-Core Mult 3x, VCO Div 4, 60x Bus Freq  16-50 , Core Freq  50-150
 - dfbrg 1, corecnf 0x10, busdf 3, cpmdf 1, plldf 0, pllmf 3
 - vco_out  400000000, scc_clk  100000000, brg_clk   25000000
 - cpu_clk  300000000, cpm_clk  200000000, bus_clk  100000000
 - pci_clk   33333333

CPU:   MPC8272 (HiP7 Rev 14, Mask unknown  immr=0x0d10,k=0x00e1]) at 300 MHz
Board: Sonos Wembley
DRAM:  64 MB
DRAM test
Test complete - 0 errors, error pattern 00000000
Using default environment

In:    serial
Out:   serial
Err:   serial
NAND:64 MB
ST Micro NAND 64MiB 3,3V 8-bit at 0xf8000000 (64 MB, 16 kB sector)
Bad block lbase 0, pbase 0, count 4096
Net:   FCC2 ETHERNET
Hit any key to stop autoboot:  0 
S0 provisionally good, KP=1, G=17
S1 provisionally good, KP=4, G=16
Boot from partition 1
Load Kernel start  10 nblock c8
Command Line (at 03fb1a08) is...

## Booting image at 01000000 ...
   Image Name:   Linux-2.6.39.4
   Image Type:   PowerPC Linux Kernel Image (gzip compressed)
   Data Size:    1489443 Bytes =  1.4 MB
   Load Address: 00400000
   Entry Point:  00400000
   Verifying Checksum ... OK
   Uncompressing Kernel Image ... OK
Memory <- <0x0 0x4000000> (64MB)
CPU clock-frequency <- 0x11e1a300 (300MHz)
CPU timebase-frequency <- 0x17d7840 (25MHz)
CPU bus-frequency <- 0x5f5e100 (100MHz)

zImage starting: loaded at 0x00400000 (sp: 0x03fb0d18)
Allocating 0x2f94a1 bytes for kernel ...
gunzipping (0x00000000 <- 0x0040d000:0x006ea6e8)...done 0x2ccee0 bytes

Linux/PowerPC load: console=ttyCPM0,38400 root=/dev/ram
Finalizing device tree... flat tree at 0x6f8300
/sbin/init: error while loading shared libraries: /lib/libc.so.6: cannot read file data: Input/output error

the last line “Input/output error” indicates a correct app partition. Unfortunately the device got shipped with a minimal u-boot setup meaning you don’t have any commands, not even the help command. After playing around with it I found the sonos command which triggers a tftpboot firmware download:
 

2. I think the device can be fixed easily by letting u-boot boot the factory partition instead of the app partition 1.
   
   Questions:
   
   1. Is there any u-boot command that can set the boot partition to the factory partition?
   
   2. is there a binary that I can use to fix this issue? Would the use of a corrupt binary trigger a checksum mismatch and automatically boot the factory partition?