Is tehre an alternative to reflash the device from the cli with a proper firmware ? Would dd work ? What would be the correct operation ? (I hardly will have access to the device physically, so can not push the "reset" button and upgrade from uboot)
The device in Comfast CF-WR650AC v2. Not sure why it matters but here you are.
The device works properly with a recent manually built firmware (from git : Powered by LuCI Master (25.184.61053~5780be0) / OpenWrt SNAPSHOT (r30279-39580b1d7b)) . but I forget to include "mtd" in the built.
So I am now searching a way to re-flash it with a proper firmware , knowing that mtd is not currently available on the device.
You can download mtd package for respective architecture.
Sun ubus call system board https://downloads.openwrt.org/releases/ -> select release (eg 23.05.5) -> select architecture/subarchitecture and get mtd...ipk package.
Copy link to wget comand line
cd /tmp
wget https://downloads.openwrt.org/releases/11.2.3/potato/red/packages/mtd-99.99.potatoarch.ipk
opkg install mtd<tab><tab>
EDIT: as said in previous post - stick with pre-built release unless you have exotic requirements.
Edit. Or if your flash is large enough install MTD as others have stated here already.
In my case back in the days I did this mistake on a 4mb device and did not had have the luxury of adding stuff later so I needed to flash over serial.