Alright, I went to my box of goodies, fished out hAP ac lite and connected it only to my computer (so no DHCP on the network)
I got into CAPS mode using following procedure:
Disconnect power->press button->connect power->wait until USR starts blinking->wait until USR stays on->release button
This way I got it in the CAPS mode and it actually seemed bricked! I got bit scared myself.
It took several minutes to appear in my list of neighbours, but even after that, I was not able to connect to it with winbox (not quite sure why).
I connected it to another device (still with no dhcp) and I was able to connect with mac-telnet from my another mikrotik device.
I tried to reboot the device, but everytime it was same - several minutes of "looking bricked" (I suspect waiting for DHCP or L2 CAPSMAN) and then connectable via mac-telnet
So, I know what you are going through but
I can assure you, your router is not bricked.
So how the heck to get out of this state of misery? Especially if you don't have second mikrotik on hand?
In my case, simple factory reset helped:
Disconnect power->press button->connect power->wait until USR starts blinking->release button
To be sure we are on the same page, here is a video for you:
https://youtu.be/-fIeNv0Pmzo
If this does not help, you may have some other issue going on. In the worst case, it may need netinstall which is whole new chapter (a lot of things can go wrong).
If you have another routerboard available, try to connect it and see if you can find your device in the neighbour list and connect via mac-telnet