Hello everyone and thank you for your time to read my long story
i have 1 router USrobotic USR9108 and a modem asusAM602
i was tierd of playing with usr9108 gui web so i decided to install open wrt
everything was good till i connect asusAM602 to USR9108 by mistake
both of them have same default gateway which is 192.168.1.1
suddnly i lost pinging the router (USR9108) but i could ping the modem asusAM602
something went wrong,it seems my router acts like a switch at the moment if i connect the router (USR9108) to any other pc i can not ping 192,168.1.1=destination host unreachable
so in my opinion either the default gateway of the router randomly changed or deleted or the cpu which is broadcom BCM6348 is damaged
i tried many default gateways in many computers no respond from router,but i still can connect the modem to router and even go to GUI modem
what should i do? how i can i completely remove the firmware and install it it again or how can i find the default gateaway for my router
please give me your hints,info anything you know
thank you so much

just unplug the modem from the router?

Any Router won't be happy if LAN and WAN are in same subnet, change the router lan ip address to 192.168.2.1, for example before connecting another with IP address 192.168.1.1.

But they are both ADSL routers aren't they? If so you are connecting the LANs and you will have an IP address conflict with same result.

i did unplug right away when it happend
i changed the router ip address,but the problem is it wont ping the ip anymore
when i change the default gateway to anything it says "destination host unreachable" meaning my default gateway is wrong or the router is turned off or the cpu of the router is...boom
but i think there must be way to reflash the router again to remove this conflict or maybe when they were making this router they put a hidden default gateway innit so if theres something like this happen they can access to to router again and reconfig it
i even connected the router with console cable but the pc " ssh,telnet,teraterm,telnet) can not see the device
any idea?
thank you

I don't see why the cpu would be damaged. And I cannot see why connecting one router to another router would trash either of them. So something else is going on (e.g., a hardware problem that was there all the time, and only just showed up, or a bricked router). If the router is simply bricked, then you should be able to recover it with the correct tools. A serial console cable, using a serial terminal program (not telnet) should show you what is going on. Are you sure you have the right serial console cable?

Your other option would be JTAG. Are there any JTAG headers?

the router itself dosnt have serial port,but inside it there are 4 pins right next to cpu
RX,TX,NC,GND but making a right tool for it its a bit hard for a noob like me
i broke one my mouse today and cut the usb connector it has 4 wires red,green,white and black
i connected then to those 4 pins i mentioned then i connected it to the serial port in my motherboard with rs232 cable
but in puttty there was nothing i changed the red with white,white with green ,did everything but still black screen in putty (ssh)
first i need to know the sequence of the pins and second i need to know the about mouse cable like what color is for what porpuse,for example white for voltage or black for ground
i searched internet about it,ppl posted some ideas but they didnt say exactly what they have done like : ok guys red wire goes to this pin,white to this one,etc etc
i even read this link:
http://blog.dvl.pl/article/2009/09/14/u ... ent-169127

be honest with you didnt help me
any idea,thank you again

oh and i forgot,there is no JTAG headers inside it too

CPU could well be damaged now - need 3.3V logic for router, PC serial ports can be +/- 12V IIRC.

Did you try connecting ADSL ports together before? There's up to 50V on phone lines!

I thought serial console was essential for OpenWrt :-

http://wiki.openwrt.org/toh/us.robotics/usr9108

yes i read that link and even a russian guys made a JTAG for usr9108 but i dont have the right tools for it
i worked all night and in the end i realized the problem is the voltage which is 12v from rs232 and red wire which is 5v
so i stopped
i either need to order it from internet or buy some of those nokia cables
the problem started when i installed openwrt firmware,i thought wow linux base bla bla better GUI but one single mistake ruind it which if it was the original usr9108 firmware it would never happend,because it wouldnt connect me to another modem instead of going offline and saying goodbye
but thank you Mr.Admin you helpd me and gave me good hits
+100000000000000 for you

finally i made it
i first made an specific rs-232 cabale which supports 3.3v
then i pluged it in usr9108 and then the serial port to pc
nothing happend,i changed the data+ and data- cabale nothing happend ( no connection in ssh,telnet,bla bla),so instead of h.d.d i realized the cpu it burning
i unplugged it and i plugged the RJ45 and pressed the reset button
suddnly the conflict gone,everything reset as normal,i removed openwrt and i installed the original usr9108
now i have my usr9108 back

ty all

And many lessons learned, no doubt.