I loaded Openwrt firmware (openwrt-18.06.2-brcm63xx-generic-FAST2704N-squashfs-cfe.bin) in my old router (tplink w8968 v3). Everything was working fine except for wifi and adsl. Realizing these limitations, I wanted to revert firmware back to its original state. So I downloaded the .bin file from Tplink website and generated stripped .bin file with 'dd' command. Tried to flash that with CFE bootloader, which didn't accept the image file (says 'illegal image'). Also tried out sysupgrade and mtd commands from ssh but it didn't work. Router's bootloader (cfe) is still intact and I can still flash openwrt image and boot it successfully.
Btw I have put block size value as 512 and tried these skip parameters 128,129,256 & 257 in the dd command to generate stripped .bin files. All of them did not work. After flashing these images, Router showed only the CFE webpage after reboot.
Please let me know how to get back stock firmware running on this router.