3HC expansion unresponsive - what to do?

sonderzug

Hi,
I have a problem commissioning my duet 3 setup on my DIY printer.
The setup is as follows:

duet 3 mini 5+ on FW 3.4.4, in SBC mode connected to an RPi 4
duet 3HC expansion v1.0
2x duet 1LC toolboards v1.1
separate 5V and 24V PSUs as well as original RPi PSU for the SBC

where the CAN daisychain looks as follows: mini5+ -> 3HC -> 1LC -> 1LC (termn.)
right now, only one 1LC board is implemented and terminated.

My issue is that the 3HC board is completely unresponsive:

all power rails seem to be OK, so 3.3V, 5V, 12V and VIN LEDs on the 3HC are lit up
the CAN status LED is off and as far as I can tell never comes on
the 1LC that is further down the CAN bus is responsive, I've already updated its firmware successfully, which tells me the CAN connection should be good (the termination jumpers on the 3HC are not fitted).
every M122 poll to the 3HC is answered by "response timeout"
I've tried setting different CAN adresses
I've tried updating the firmware to no avail (CAN response timeout)
I've tried updating the bootloader to no avail (CAN response timeout)

I've come across this thread where David Crocker mentions some firmware problems with earlier versions.
The boards were purchased back in february '22 through a german reseller, the mini 5+ was on FW 3.2.2 and the 1LC toolboard was on 3.3b - is it possible that the 3HC is on one of the FW versions that is mentioned in the above thread?
What are my options aside from force updating the bootloader using the Atmel ICE which I don't own?
Any other ideas?

thank you as always,
best, Niklas

sonderzug

FWIW I've left the setup powered up for the hours since my last post, and the 3HC did not eventually come alive unfortunately....
@dc42 I hate to "summon" you like this, but this machine is supposed to be exhibited at formnext next week, and I'm getting a bit nervous. Any thoughts?

thank you,
Niklas

dc42

@sonderzug I approve a warranty replacement. Please send an email to warranty@duet3d.com and include a link to this thread in your email.

sonderzug

thank you, I've been able to buy a replacement in short term and will make use of your replacement offer afterwards.

best, Niklas