I connected my Xbox 360 after 6 months and connected it to the LED, but it was not showing up on either HDMI 1 or HDMI 2. The remote is also not connecting (through wireless), which shows on Xbox but rather it keeps flashing. I have changed the HDMI cables too.
A bit confused on exactly what the problem is. However what i could get was that the controller has its LED just flashing and not connecting right? Most often it's because the batteries are low and need either new ones or fully charged ones. If that doesn't work, then there's a problem with either the connection sender or the battery case. To that extent i would recommend getting a new controller.
If no controllers can connect to the console at all, I can only imagine that would be because the console's receiver isn't functioning properly or damaged.
I hope for the best, since this is all I know.