After installing a slightly modified image to test OpenWrt support my router is stuck with that firmware version. Any advice is appreciated

Non working CFE bootlog with "tftpd" on router and tftp-client from a linux pc

CFE for WNDR3400v2 version: v1.0.15
Build Date: Mon Sep  5 13:35:48 CST 2011 
Init Arena
Init Devs.
Boot partition size = 262144(0x40000)
Found a 8MB ST compatible serial flash
et0: Broadcom BCM47XX 10/100/1000 Mbps Ethernet Controller 5.60.127.17 
CPU type 0x19749: 530MHz
Tot mem: 65536 KBytes

Device eth0:  hwaddr 00-FF-FF-FF-FF-FF, ipaddr 192.168.1.1, mask 255.255.255.0
        gateway not set, nameserver not set
Loader:raw Filesys:tftp Dev:eth0 File:192.168.1.2:vmlinuz Options:(null)
Loading: ... 7307322 bytes read
Entry at 0x807bfc10
             
Image ID : U12H187T00_NETGEAR
Reading ::

workinig flash from stock to openwrt

CFE for WNDR3400v2 version: v1.0.15
Build Date: Mon Sep  5 13:35:48 CST 2011 
Init Arena
Init Devs.
Boot partition size = 262144(0x40000)
Found a 8MB ST compatible serial flash
et0: Broadcom BCM47XX 10/100/1000 Mbps Ethernet Controller 5.60.127.17 
CPU type 0x19749: 530MHz
Tot mem: 65536 KBytes

Device eth0:  hwaddr 74-44-01-37-C6-69, ipaddr 192.168.1.1, mask 255.255.255.0
        gateway not set, nameserver not set
Startup canceled
CFE> ^C
CFE> ^C
CFE> tftpd
Start TFTP server
Reading :: Done. 3018752 bytes read
Reading :: Done. 3018810 bytes read
Board ID : U12H187T00_NETGEAR
Image ID : U12H155T00_NETGEAR
Reading :: Done. 4526138 bytes read
Programming...done. 4526138 bytes written
Write len/chksum offset @ 0x006FFFF8...done.
Decompressing..........done


CFE for WNDR3400v2 version: v1.0.15
Build Date: Mon Sep  5 13:35:48 CST 2011 
Init Arena
Init Devs.
Boot partition size = 262144(0x40000)
Found a 8MB ST compatible serial flash
et0: Broadcom BCM47XX 10/100/1000 Mbps Ethernet Controller 5.60.127.17 
CPU type 0x19749: 530MHz
Tot mem: 65536 KBytes

Device eth0:  hwaddr 74-44-01-37-C6-69, ipaddr 192.168.1.1, mask 255.255.255.0
        gateway not set, nameserver not set
too long file.
LZMA boot failed
Loader:raw Filesys:raw Dev:flash0.os File: Options:(null)
Loading: .. 3780 bytes read
Entry at 0x80001000
Closing network.
Starting program at 0x80001000
[    0.000000] Linux version 3.6.11 (tenchi@tenchi-htpc) (gcc version 4.6.4 20121210 (prerelease) (Linaro GCC 4.6-2012.12) ) #3 Sun Feb 24 22:46:06 CET 2013

Netgear stripped the CFE on this model too.
In contrast to the WGT634U (Thread) the bootloader doesnt seem to have printenv / setenv settings.
Somehow Lan is broken if OpenWrt gets booted (some vlan/port issue maybe?) so for now its CFE ...

TFTPBoot gets stuck too - maybe some missing parameters ?

Device eth0:  hwaddr 00-FF-FF-FF-FF-FF, ipaddr 192.168.1.1, mask 255.255.255.0
        gateway not set, nameserver not set
Loader:raw Filesys:tftp Dev:eth0 File:192.168.1.2:vmlinuz Options:(null)
Loading: ... 7307322 bytes read
Entry at 0x807bfc10
Loader:raw Filesys:memory Dev:eth0 File::0x807bfc10 Options:(null)
Loading: .. 33 bytes read
Entry at 0x80001000
Closing network.
Starting program at 0x80001000

factory logs are available in the wiki: WNDR3400v2