Installing NetBSD 9.1 on USB stick, not booting

[Mayuresh <mayuresh%acm.org@localhost>]

I have installed NetBSD 9.1 on a USB stick. I think earlier installers
used to ask about bootcode. 9.1 installer didn't ask me about it. The
installation seems fine but the stick is not booting.

I tried manually setting the boot manager (fdisk -B) though it didn't
work. I do not have a trace of all my attempts but finally it rendered the
USB stick read-only. Wasn't able to make it writable again, also tried on
Linux.

I got a new replacement stick now and I am back into the same situation -
installation is complete, but it won't boot. What exactly do I need to do
to make it bootable. I don't need it to work with the hdd of the host or
grub etc. Just need plain simple bootable usb stick that would boot into
NetBSD.

-- 
Mayuresh