not quite sure what you are saying you did....I'd gather this would reset the config of the current (possibly not working firmware) only.
You*ll have to activate the (old), backup firmware that is also present in the board,
Read the extra "Note" below the instructions.
RouterBOARD reset button
RouterBOOT reset button has three functions:
Hold this button during boot time until LED light starts flashing, release the button to reset RouterOS configuration (total 5 seconds)
Keep holding for 5 more seconds, LED turns solid, release now to turn on CAPs mode (total 10 seconds)
Or Keep holding the button for 5 more seconds until until LED turns off, then release it to make the RouterBOARD look for Netinstall servers (total 15 seconds)
Note: If you hold the button before applying power, backup RouterBOOT will be used in addition to all the above actions. To do the above actions without loading the backup loader, push the button right after applying power to the device.
...so, whichever variant you choose...press - and keep holding down - the reset-button before applying the power to the device.
I had a similar situation once, when having my first encounter with the CAP-ac...did struggle as well, and had to try several times.
Maybe using the RooterBoot method, together with netinstall option is the safest one to make sure a stable version will end up on the device.