hi team, how is going there?
I have bought this usb to serial CP2102 in amazon. When I want to try to use this in my w8970 I just got a black screen. Could you tell me if someone else had the same problem? (I mean, trying use cp2102 with w8970). Thanks for your help in advance
Which terminal emulation program are you using?
Are the serial settings correct?
Have you connected the cables properly on the board? The TX from CP2102 goes to RX on the board and vice versa.
Hi Thanks for your reply
Well I'm using Putty and I have connected as the best practices recommend. Perhaps my routers doesn't work anymore 
Per example When I just turn on the device the USB-TTL device recieved something because its mini-led RX blinks
115200, 8N1 ?
Yes
Also someone mentioned wrong TX-RX order here so try the connections both ways.
Already done
connect tx to rx on cp2102 and type something if you get output it works. maybe your router is bricked.
It's quite possible that you can only attach the tx line of your usb2serial adapter after powering on the router (a second or two), because it may leak voltage into the SOC and partially power it, leaving it in an uninitialized state.
If this router is bricked,is the there any chance to get back?
you'd need ch341a and u-boot/art for that device
what does ch341a mean?
ch341a is a relatively cheap USB device (well, chipset) that can be used as SPI-NOR (flash) writer with flashrom.
Edit: If you already own a Raspberry Pi, that might also be an alternative for flashing SPI-NOR chips, you generally want a SOIC8 clamp as well (which makes it easier to connect flasher and chip than temporarily soldering on wires).
With the price of (used) devices like the BT Home Hub 5 Type A or the Arcadyan VGV7510KW22 (o2 Box 6431) or a number of other (ISP branded) lantiq devices being in the sub 5-20 EUR range, it probably isn't economically viable to spend much money (soldering iron, solder, flux, desoldering pump, solder wick, serial console, spi-nor flasher, soic-8 clamp, cables - neither of those are particularly expensive, but it adds up very fast) on trying to rescue your device though.
Thanks mate for your answer. You are right.
Thanks everyone for your helps and answers.