Linksys EA8500 Bricked no reason

I was running dd-wrt

Thank you for sharing your thoughts.
Ok, make sense.
Anyway to find out which one it is?
And what the root cause might be?
And is it solvable?

And when I fiddle a little bit with the serial wires I get characters as output. Also when turning off and on. a few dots.

And is this the right tx and rx setup?

To confirm your PC terminal sw + FTDI board is ok, pls short the Tx/Rx headers of the FTDI board, no connect to the router, when you type a char from the terminal (putty?), you will receive the same char echo from the Rx wire.

And many things could happened, for example, connection wire not good......I met several times.

strange, my EA8500's power light in the front does not blink instead goes to turn on, and its ethernet lights and buttons do not turn on

same, one time i had access to the serial using my cp2102 usb to ttl module but before i got to that i had this image first in the top
image

like the jumbled letters and the power button faded and turned back on again
after that i got to the text that says "press any putton to exit boot (2)" something like that and after that i couldnt press anything and the jumbled letters are there again

i had got a signal meaning, maybe, the bootloader isnt dead

the 30-30-30 reset wouldnt affect your router if you flashed the linksys firmware twice because it is said in the openwrt table of hardware, and some people report that when they do the 30-30-30 reset the other firmware wouldnt boot and that includes me.