NSA-320 kwboot doesn't work; hangs after fully sending image (1 reply)

Hello,
I'm trying to upgrade my ZyXEL NSA-320 u-boot to prepare it for debian/openmediavault. Before doing anything I wanted to make sure kwboot works, so I am trying to kwboot both the new u-boot and also the stock mtd0 backup I took but all u-boots I try give the same result:

My serial port is set to baud 115200 - data bits 8 - stop bits 1 - flow control none - parity none

~# kwboot -t -B 115200 /dev/ttyUSB0 -b uboot.2017.07-tld-1.nsa320.mtd0.kwb -p
Sending boot message. Please reboot the target... -
Sending boot image...
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[Type Ctrl-\ + c to quit]
?

~# kwboot -t -B 115200 /dev/ttyUSB0 -b mtd0.backup -p

gives the same result.

After the image is loaded it just gives this strange unicode symbol and just sits there. I'm using a FTDI chip and i can get serial console just fine and boot into Arch already and control it with no problems. I've got TX,RX and GND connected only (no VCC).

kwboot version is:

apt install u-boot-tools
Reading package lists... Done
Building dependency tree
Reading state information... Done
u-boot-tools is already the newest version (2016.03+dfsg1-6ubuntu2).
0 upgraded, 0 newly installed, 0 to remove and 0 not upgraded.

OS is Ubuntu Bionic 18.04 LTS.
Trying without -p gives few blocks of sending and then the original u-boot boots and then gives xmodem error so I think -p is needed.

I connecting the pins directly to the ftdi chip using thin cables with female ends from each pin to the corresponding on the chip.

What else do I need to check ? Anything I can try ?