Modifying u-boot and flashing firmware from inside the limited Linux shell - possible?

[qumuq-til]

I've tried getting into a boot-password-protected HI3516EV300 device using the burn utility, without success. Then I've tried shortening the pins but it didn't affect u-boot behavior whatsoever. Then I was somehow able to gain a limited shell access using the same pins, so that it drops me into Linux shell after a failed boot. Is it possible to use this shell to reset u-boot password, flash a new generic boot partition or flash the firmware in its entirety? The openipc flashing manual seemingly deals with u-boot commands which I don't have here.

Additionally, does openipc firmware image contain bootloader as well, or do I need to flash it separately if using a hardware programmer?