I found out the there is no need to drill the keyboard.
There are small pins, but they are difficult to remove. And there are many.
I removed all of them and take out the keyboard. It is glued to the metal frame.
Once you take it off the metal frame you can see the circuits.
They are small and you need a Magnifying glass to follow them.
All my not working keys are on the same line. But on the same line there are also other keys. I'm almost sure some welding is broken. But I need more time.
WOW! Thank you for the pictures and robust response! Have you thought of (and I am sure you have) using a multi-meter to test the connectivity (pin-out) of the welds you mentioned? Understood that your dealing with micro-circuitry and often times a multi-meters leads are often times too big unless you use a pin-out adapter. I have used this method many times when testing some sort of electronic device that has gone dead or malfunctioned some manner.
You more than likely already have a long list of browser bookmarks pertaining to the tear-down of the Surface Book 2 - here is one I stumbled into that might/might not help you in your endeavor. ( Microsoft Surface Book 2 Teardown ).....What would REALLY help would be an actual circuit diagram - this would help in testing out the embedded wires. I would really like to upgrade my Surface Pro 4 SSD, but I am unable to find a complete part listing/reassembly guide. I can find a 1TB SSD for around $250 on Ebay, but full circle back to the reassembly conundrum. Yayy.
Question - IN your pictures above, the third picture from the top shows a part bin with small rivets or something like that - Are these the "PINS" you are referring to? Do they 'Snap!' back into place? Just curious if they are a "one-way" use once part. OR, perhaps can they simply snap back into place providing a "good-as-new" repair? (I just depleted the world supply of quotation marks).
Thanks for listening to me ramble - Things like this really wind me up. Again - thanks for your reply.