MID button replacement

Maybe...

I never had an E36 OBC open but judging from pictures I found online at least some models use the same button mechanism as the E31 MID. The problem is that there have been 2 different styles of keyboard mechanisms in the E31 MID and at least 2 in the E36 MID as well. I have pictures comparing both E31 styles but I can't find them back, sorry. Here's what the later style looks like:

An overly complex and fragile design.

Please note that depending on what fails (usually the plastic levers), you will not be able to repair individual buttons. You will have to transplant entire groups of buttons. So if you think you can be smart by getting a donor MID/OBC with different dead buttons, think again.

The E31 keyboard mechanism is secured to the board with retaining clips and can be removed easily as you can see in my picture. It is however possible - I don't know for sure - that the early keyboard mechanism does not fit the holes and cut-outs in the later PCB (and vice versa). I also saw a picture of an E36 keyboard that was secured with melted plastic tabs. I don't think you could easily transplant this particular keyboard mechanism. If you can't transplant the keyboard mechanism easily I would simply desolder the E31 keyboard PCB and solder the E36 one in place. I would be very surprised if it's not pin compatible... Both use the same 15-pin ribbon cable.

PS: The above is only true if you get the 18-button E36 OBC. The other variants do not have keyboard parts you can reuse (apart from the 1/10/100/1000 keys perhaps).