Hi there!

Yesterday one of my routers has been hacked during initial tuning process. Now I'm aware of the mistakes of tuning process while being connected to the Web. So do not throw stone at me, please. Any advice will be welcome and appreciated.
Here are the details:

The router is RB952Ui-5ac2nD. After hacking the rights of such user as ADMIN have been changed to READ, there has been created a new user - USER1 with rights FULL, the RESET button has been disabled. So all I have is just user rights allowing me, as you know, nothing. The branch System\Routerboard\Settings shows that Reformat Hold Button value has been changed to 00:04:50. All logs have been deleted. Any attempts to keep the Reset button pressed fo 4:50 or any other duration of time completed with no results. The utility Netinstall, as you understand, is useless whereas the Reset button is not available to force the router into netinstall mode. When the button is pressed the USR LED flashes about once a second. After released - the router restarts, but doesn't reset. Any ideas of how to un-brick the router and bring it back to life?
I used Google to investigate the issue but any hints found appeared to be useless.

PS: this model of router doesn't have any other RESET terminals on board so such advices as shorten them will be of no use either.

Thank you in advance for any hints, folks.

Best regards,
Viacheslav.