Single, shows up, says battery status okay and asks to calibrate. Everything looks like it should be okay, but it isn't. I've seen people using cork under the contacts, didn't notice your post re the batteries though, I'll have a look and might give that a go.
People use cork, I used a tiny cutting from Kenco Milincano instant coffee lid.
CR1 batteries with a little bit baby oil on them.
If you are touching the internals/gold contacts in the pedal, be VERY gentle and careful. They snap off if you even look at them the wrong way never mind touch them.
And when screwing the doors back in, double, triple check they are lined up and threaded correct as the yellow rubber band thing on there will snap on you if you have them anything other than perfectly lined up on the thread.




), but if I tweak the saddle position and/or post and get niggles I check the angle between hip/just below kneecap/ankle with normal foot extension when pedal is at bottom dead centre. 25 to 35 degree bend works for many, ~30 degree works for me.