The DIY batteries have Solder tabs wooded on so it's not a difficult job for somebody that has soldering skill however you won't have replacement button switches or experience so @UAL assessment is correct in that's the best bet. I would prob buy an actual key from the online dealer that sells real keys for a second key.

I'm saying literally that is what I would do as I'm planning to order one soon so I can do the reflow/button switch/ battery replace on my only key which remote stopped working about 18 months ago.

I have read not exaggerating over a dozen similar threads where the final result is a dealer key.

In those threads, I can estimate about a 15:1 ratio of didn't to did work with non dealer solutions and the :1 examples are where the EWS hardware is removed to pair with a new key or the guts are swapped to a new key. The only other option I've seen with solid success is cutting the blade off an eBay key to use as a separate remote.

Not saying you won't resolve this issue but I think your car is stuck in a mode where you can't program keys likely do to the open roof.

In that case a new dealer key will still not resolve your issue there problem is you don't know if your primary key battery is functional or the remote is broken on it so you have no control.

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2011 E70 • N55 (me)
2012 E70 • N63 (wife)