USB method suggested by @Willo3092 didnt work.Try the USB tools by willow first. If you stilll dont have any joy, you should be able to reset the password in the Network > password menu. You wont be prompted for the old one.
Are any errors shown when you go in plugin menu? Do you have parental controls set?
Just to clarify only the IPK file?Ok, if error disappears before you can see it, not to worry. I think we can solve your issue this way.
Download full image backup suite from here: Dima73/automatic-full-backup
Transfer ipk to your USB stick. With no menus showing on receiver, plug the USB stick in, it should hopefully allow you to install it. Once installed restart.
Go into the plugin, you will have to select the extracted image folder on USB stick and there will be an option to flash