I sorry to hear this but indeed something must be defective in the hardware. Beside the fact that it won't set up the netwerk interface , especially these messages you found in boot.log file are worrying.
You mentioned in your first post that it stopped working with the original firmware, was that also not being able to contact it ?
Still I wonder how these last messages
ERROR: lacfg_init fail read version
ERROR: lacfg_load_key no map defined
write_byte_storage : error loading key=power
ERROR : writing into the storage
error setting power on
ERROR: lacfg_cleanup no map defined
can come in the boot.log file as after adding the message "rcS" finished there are only these commands execute
cat /boot.log
sleep 3
exit 0
none of those can add something to the boot.log file, so who or what is adding that info....and why is it shutting down by itself