Have new Mini 4 and while the flashing light works in the rear and it comes on with the headlight turned on, there is NO Brake light?
I've disconnected and re connected all the wires to no effect? Any ideas?
Does the brake light fail to light with both front and rear brake? If it's only one, I'd look for a bad switch in the brake handle. If both, maybe a controller problem? Rad is quite good over the phone with these sorts of things, so I'd suggest giving them a call and make sure you can access the bike and test things while talking to them. They helped me fix an annoying little squeak I just couldn't find, but walking me through a few tests.
Good luck.