Did you disable your DHCP on your secondary router? And that you can not access the router at all? Well if that is the case then here is a useful tutorial video for you on how you can access your Secondary router even if the DHCP is disabled. And no you will not be required to reset the router and go through all the setup.

Regardless, if you have manually disabled the DHCH or are using the router as an Access point, then in most cases, you will not be able to access the secondary router. You will receive some errors while using the old IP address, but by doing some simple IPV4 setup you will be able to access your secondary router without doing any resetting. It will then be very easy for you to change the SSID  or anything.

We really hope this video has been useful to you.