Might try a reset if there is such a feature on the 2nd switch. Try connecting a PC or Laptop directly to the 2nd switch with out any other connections connected.
Ya, you'll need to find a time frame when you can try all of this out with impacting needed operations.
Ok, if the removal can't be done, at some point when traffic is low or you can get a short period to test, can you disconnect the 1st switch and leave the other connected or connect in place the 2nd switch with the 1st switch to see if you can access the UI? Just a troubleshooting step to see if you can gain access with out any other switches.