kally,
> root@hal4:/hal/u-boot# ./tools/kwboot -b
> ../uboot.2023.04-tld-1.ds411j.kwb -s 0 -B 115200
> -t /dev/ttyUSB0
> This exact command was working before but it is
> not anymore, the NAS does not trigger anything
>
> I suppose my image is not corrupt enough and the
> NAS tries to start it without looking at UART
I'd doubt that was the reason. If the box BootROM receives the handshake from kwboot, it will ignore every other boot sources and switch to UART booting only. And the BootROM always listen to the UART port before considering other boot sources.
You could try: unplug the power cord and let it sit for a while, and try again.
===
It's hard to guess the problem without seeing the flashing session log first. It's always best to keep the log when test booting and flashing a new u-boot.
-bodhi
===========================
Forum Wiki
bodhi's corner (buy bodhi a beer)