@subhranil, in fact the ethernet ports are dead.
I believe (just an hypothesis) the web recovery is not automatically activated because uboot finds a valid kernel and tries to load it. And what happens is what it seems kernel gets stuck for some reason and does not report any error.
That's why the device ends up bricked without any activity in the ethernet ports because kernel did not load and web recovery is not activated. TFTP is also not an option.
Therefore the only option is to attach a UART and activate web recovery manually via serial console before kernel load.