I have a 51 mini one and I had the same problem recently. My remote wouldnt work and I had to use the key to get into the car. At the same time, my right indicator started flickering really quickly when I indicated to go right.
Cut a long story short but I took it into the local dealership and they said my car needed a new BC1 unit which is nearly £500!! The BC1 controls all electrics on the right side of car, I think? I did have the work done but when they drove my car back to my work after doing the work, my right indicator was still flickering quickly and I kicked up a right stink.
They agreed to take out the new BC1 unit and then put my old one back in, reset the BC1 unit and since then, my key remote works and my indicator has gone back to flickering in the normal way...... until today................
I have just been on the motorway, indicated to go into the right hand lane and the indicator has started flickering really quickly again......
I am hoping to ignore it and hope that perhaps my car was having a bad day - but I am starting to think that I might need that new BC1 unit after all!!
I am going to post a thread on here to see if this has happened to anyone else.
Let me know what the garage say about your key remote - perhaps you also need a new BC1 unit?