Booting Console on 400t with A1416A

Maybe someone has had this problem before:

I have a 400t with an A1416A display interface, diskless, connected to 
my network.

I have a i386 box running NetBSD/i386, with the necessary services, NFS 
exports and configuration files. I also have untarred some 
NetBSD/hp300-1.6.2 sets to the exported filesystems.

When I boot the 400t in remote mode[1] the system works fine. I even 
tried its functionality by building a custom kernel. It took about 1 
hour for the make depend, and 5h30 for the make, but it works.

When I boot the machine in local mode[2], the system grabs the 
bootstraploader SYS_UBOOT, and loads the kernel. That takes some time, 
but gets loaded eventually. Then it shows a line telling me the 
entry-point of the kernel, and that's it.

Nothing.

Also no indication that the system is running with its console output on 
a (to me) invisible display. The status lights are all off, no heartbeat 
blinkyblink, no network activity.

Does anyone know something about this issue?

Thanks,
Alex.

[1] In the firmware I selected the RS232 serial port as console.

[2] The console is selected in the firmware, using the A1416A as display 
device, and a HIL Keyboard and mouse connected to the HIL port. Of 
course the system is set in HP-UX mode.