Found another Wii U premium console today, just the main unit. The console does actually boot up, it still had NSMBU disc inside
I already have a spare set of power supplies and a white gamepad from a basic model (still need to test if it works ok).
Just charging the gamepad now and I'll see if I can sync it up.
If I can't get the gamepad to work, I'll try syncing the black gamepad from my premium set (that I do know works fine).