Some special keys do not work

Hello, I have a MacBook Pro from 2012, A1398.

The following keys are no longer working.

• left shift
• left ctrl
• left alt
• left cmd
• right shift
• F1 - F9

On an external keyboard these keys are working.

SMC reset is not possible as the according keys do not work.

Any idea except exchanging the keyboard?

Thank you

Thank you Dan.

Actually I replaced the battery yesterday and the problem has started. Could you please describe where the battery should touch the keyboard cable.

For me it seems separated (I have not removed more then the battery so far).

I tried to search for a cabling diagram for the keyboard to see the connections with all the keys which are not working. I removed the keyboard connector and cleaned it (further if I shutdown, most of the time I have to remove the power cable and the battery cable, press the power button and replug the power cable, then the system boots, otherwise not. Afterward I also re-connect the battery cable. For this additional problem I would like do the SCM reset).

BTW - For upper case I currently work with caps lock, or using the keyboard viewer tool - there I also see clearly which keys are working. This beside the workaround with an external keyboard.