I have bricked my archer c20i by trying to flash an image without uboot.
I've tried to follow instruction at https://pwassi.privatedns.org/lede/archerc20i/ but since i dont have a RPi (and i don't really want to buy one just to unbrick my router) i don't have any idea what to do.
I went as far as desoldering U18 chip.
Here are my questions:
Where do i need to solder wires for spi?
can i use something else instead of RPi? i have ft232rl programmer i use with arduinos, as well as arduino mega, nano and pro mini. It seems that i should be able to achieve something with my stuff but i don't know how.
You need to remove the flash chip (U18) from router PCB and connect it to some flash programmer or Raspberry Pi/any other device which can do SPI NOR flashing.
Arduino should do the job: https://www.flashrom.org/Serprog/Arduino_flasher. But make sure you have a proper voltage level on pins - have a look at that red note on top of the website. SPI NOR chip you have in router uses ~3.3V level logic!