My hAP RB951Ui-2nD got into a state of insanity, it seems.

It hardly boot up, lights show impossible states, and when it finally get to do SOMETHING useful after numerous watchdog reboots, the web interface is not accessible.

The quick summary page is entirely blank, and trying to access any subpages by hashtag make it repeatedly poll "jsproxy" file without any visible feedback.

I can access it by SSH sometimes, at least I dumped its config and made sure it was not changed from the last time I backed it up.

If there anything I can do about it? Can I trigger an upgrade over SSH? Perhaps a new FW get it to senses.

Try using NetInstall to reinstall the firmware. I've had to do it on a few devices to get them working (some right out of the box). It's a little tricky to setup, but dead simple once you do.

Last time I tried it, it straight up does not work. But I'll try again.

With netinstall it is important that you exactly follow the instructions, not "I'll glance over that and do what seems logical".
Also, it requires some practice. Most users do not get it right the first time, spend a lot of time on it, and once they have it working they do not understand why it was so difficult.
So that will probably remain like that...

Can you try with another power supply?
The symptoms could be those of a problem with not enough power.

If you have access to the console via SSH, you may want to try using the ROS command to etherboot:
https://help.mikrotik.com/docs/display/ ... l-RouterOS
it might be easier than fiddling with the reset button.

What I don't understand from the documentation is why it can't be coded to let the user choose what interface it wants to work with.

THAT seems logical.

(A side note: winbox let me in, upgraded to 7.15, no dice, webfig still dead.)

Can you try with another power supply?

It's PoE powered using its original power source and an original injector. Was working fine for several months.
I'll try to plug the power directly, but that's really not what I wanted from it.

What I don't understand from the documentation is why it can't be coded to let the user choose what interface it wants to work with.

There is a command line version that does have that option.

(A side note: winbox let me in, upgraded to 7.15, no dice, webfig still dead.)

Because the resolution suggestion was/is: netinstall. Assumption: you did not disable www service somehow.

I've managed to get the router show up in netinstall, but then a package disappears from the list.
I suspect architecture mismatch. Though, there's only one hAP RB951Ui-2nD…

…a few moments later…

Turned out, it wanted MIPSBE package. Flashing now.

Eh, no. It still does not boot right.

It run up to "flashing finished successfully" and sit there. I power cycled it, but it is not coming up in the network.

Should I specify IP when flashing, or using a configuration script is enough?

If you managed to correctly install routeros-7.xx-mipsbe.npk using Netinstall. And now the equipment turns on. You must use Winbox, in the Neighbors area and connect via MAC. Since it does not have a dhcp server or anything installed