About the machine.
It has an NVIDIA Geforce Go 7300. The processor is an Intel Core 2 Duo T5500 (I checked and it should be an amd64). Ram should be 2GB (that is what I see from dmesg).
About the commands, I have to manually rewrite everything I see since I don't have access from the machine, so I'll try to do my best.
I still don't know exactly how the boot process in a Unix system works but from running 'dmesg' after the syscall error I can see that he starts loading some drivers (I guess?), of various things (like ACPI), and everything seems to go alright until this line:
[4.4812925] WARNING: 1 error while detecting hardware; check system log.
[4.4812925] boot device: sd0
[4.4812925] root on dk1
[4.5012926] root file system type: ffs
[4.5012926] kern.module.path=/stand/amd64/10.1/modules
[4.5012926] nouveau0: NVIDIA G72 (046700a3)
[4.5212927] nouveau0: bios: version 05.72.22.58.30
[4.5212927] nouveau0: autoconfiguration error: error: imem: unable to map PRAMIN BAR 2: -35
[4.5212927] nouveau0: autoconfiguration error: error: imem ctor failed, -35
[4.5212927] nouveau0: autoconfiguration error: unable to create nouveau device: 35
[4.5212927] WARNING: preposterous TOD clock time
[4.5212927] WARNING: using filesystem time
[4.5264819] WARNING: CHECK AND RESET THE DATE!
[4.6812924] panic: cnopen: no console device
[4.6812924] cpu1: Begin traceback...
[4.6812924] vpanic() at netbsd:vpanic+0x183
[...]
and then the journal goes on listing the same error I already mentioned in the first message.
So apparently the problem seems related to the nouveau driver (I guess?).
** Tried with 'boot -c' and then 'disable nouveau', then 'exit'. Boot starts but get stuck at:
[4.7151799] swwdog0: software watchdog initialized
and then after an eternity
[264.7352127] sd0d: error reading fsbn 64 (sd0 bn 64; cn 0 tn 2 sn 0)
It's not the first time I encounter this error. It was also showing up on normal boots sometimes, but I just ignored it and rebooted the machine until it worked. (in this case, even repeating the process multiple times, it doesn't seem to be booting anyway. The trick just works in normal boot).
Also, fun fact, when the system hangs here and I reboot the machine (pressing down the power button and then pressing it again), if I keep the usb stick in the same slot I get:
Disk error on boot
Operating system not found
What I need to do is use another USB slot and then it magically works again.
[UPDATE]
I just realized I was using the 'exit' command, but then I checked the available commands in the userconf prompt and it had 'quit'. I typed quit and it booted, And I am now seeing the installation screen. I tried rebooting and entering a couple of times and it does indeed boot only if I disable the nouveau driver.
[UPDATE OF THE UPDATE]
Apparently it wasn't the 'exit' or 'quit' the problem. Even with 'quit' sometimes it just hangs and the boot process halts:
[ 4.6968325] swwdog0: software watchdog initialized
[9.7468324]: BBB reset failed, TIMEOUT
[14.7468331]: BBB bulk-in clear stall failed, TIMEOUT
[19.7468334]: BBB bulk-out clear stall failed, TIMEOUT
And then it just starts repeating itself over and over until I kill it.
So apparently it just random. I just got it to boot once and then never again.