hi,
   just trying this for the first time and from a Windows PC.
on booting my router i get the following:

ROM VER: 1.1.4
CFG 06
NAND
NAND Read OK
DDR autotuning Rev 0.3d
DDR size from 0xa0000000 - 0xa7ffffff
DDR check ok... start booting...
                                             
so I assume all is good next i power off and short to ground the boot selector and i get :
ROM VER: 1.1.4
CFG 04
UART

I send the file using Realterminal lede-lantiq-bthomehubv5a_ram-u-boot.asc
I don't see any thing to screen and the file transfer completes after around 3 mins.

Am i missing a step?