It’s possible the file is damaged, so using the edit which you can run, try uploading this fresh copy of the config app.
index.htm (155.6 KB)
If that doesn’t work, using a laptop or desktop, try running the debugger (F12) and refreshing the app (F5). Note the “console” for error messages and then do it again with “network” selected and post the output.
Given your unit is six years in service, the SDcard may be getting tired. It would be a good idea to replace it while you are at it. You should be able to just copy the old to the new.