I can confirm the symptoms you describe - because I had the very same experience.
Surface Book kept on crashing after the firmware update. Mostly multicolor cross hatch pattern, sometimes bluescreens with random stopcodes (I guess I now have seen them all) and in very rare occasions freezing screen. The record was 30+ crashes on a single day.
I mean this can happen, no piece of software is totally error-free, but support was not very helpful if you asked me. They captured 20h of my precious time with ever repeating same questions (I had contact to 9 support agents, as I fell out of conversations due to crashes and have been reconnected to a different agent) and ever repeating same tests (like checking for windows update, even when the machine just rebooted three minutes ago), querying windows versions and running different diagnostic tests (surface diagnostic too, memory test, ...).
Even when I multiple times mentioned, that I assume the problem is due to a bad firmware upgrade and referred to this very forum post, they kept on executing their checklist with checking for os and hardware issues.
In the end, they got the reboot problem kind of "solved", because now my Surface Book is not booting anymore, after trying to reset windows, during which my Surface Book crashed again. :-(
This was past Wednesday, past Monday my replacement arrived - and doing good so far (even when I did not succeed from preventing installing firmware upgrades as well).