So I have tried serial console for unbrick the router.
The serial pin on PCB of router found dead. SO I have connected the TX RX GND as on this image
http://s19.postimg.org/tnah7qg8j/tl_wr741n.jpg.
The serial pin connected via CA-42 data cable and using putty/v Hyperterminal / Herculies.
I got the following display--
U-Boot 1.1.4 (Dec 11 2009 - 15:56:55)
AP91 (ar7240) U-boot
DRAM:
sri
#### TAP VALUE 1 = 9, 2 = a
32 MB
id read 0x100000ff
flash size 4194304, sector count = 64
Flash: 4 MB
Using default environment
In: serial
Out: serial
Err: serial
Net: ag7240_enet_initialize...
No valid address in Flash. Using fixed address
tp: cfg1 0xf cfg2 0x7014
leth0: 00:03:7f:09:0b:ad
eth0 up
No valid address in Flash. Using fixed address
: cfg1 0xf cfg2 0x7214
eth1: 00:03:7f:09:0b:ad
ATHRS26: resetting s26
tATHRS26: s26 reset done
eth1 up
eth0, eth1
Autobooting in 1 seconds
pll## Booting image at 9f020000 ...
Uncompressing Kernel Image ... Error: Bad gzipped data
GUNZIP ERROR - must RESET board to recover
Resetting...
U-Boot 1.1.4 (Dec 11 2009 - 15:56:55)
AP91 (ar7240) U-boot
DRAM:
sri
tpl#### TAP VALUE 1 = 9, 2 = a
32 MB
id read 0x100000ff
flash size 4194304, sector count = 64
Flash: 4 MB
Using default environment
In: serial
Out: serial
Err: serial
Net: ag7240_enet_initialize...
No valid address in Flash. Using fixed address
: cfg1 0xf cfg2 0x7014
teth0: 00:03:7f:09:0b:ad
[pleth0 up
No valid address in Flash. Using fixed address
: cfg1 0xf cfg2 0x7214
eth1: 00:03:7f:09:0b:ad
ATHRS26: resetting s26
ATHRS26: s26 reset done
eth1 up
eth0, eth1
Autobooting in 1 seconds
After pressing "tpl" the command prompt appears "ar7240> > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > >> > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > >
> > > > > > > > > > >" but it hangs. After that no command accepting.
U-Boot 1.1.4 (Dec 11 2009 - 15:56:55)
AP91 (ar7240) U-boot
DRAM:
sri
tpl#### TAP VALUE 1 = 9, 2 = a
32 MB
id read 0x100000ff
flash size 4194304, sector count = 64
Flash: 4 MB
Using default environment
In: serial
Out: serial
Err: serial
Net: ag7240_enet_initialize...
No valid address in Flash. Using fixed address
: cfg1 0xf cfg2 0x7014
teth0: 00:03:7f:09:0b:ad
[pleth0 up
No valid address in Flash. Using fixed address
: cfg1 0xf cfg2 0x7214
eth1: 00:03:7f:09:0b:ad
ATHRS26: resetting s26
ATHRS26: s26 reset done
eth1 up
eth0, eth1
Autobooting in 1 seconds
tplar7240> > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > >
> > > > > > > > > > > > J9QIIUAQ>
ar7240> > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > >
> > > > > > > > > > >
Some time shows un-endable unidentified symbol after pressing "tpl".
Please help for serial console works correctly and accept command.
And no-hang problem and un-endable un-identified symbol.
Please help...