i had the yellow bang, too. when i first installed, i was on battery and was informed i needed to charge the battery before proceeding, did that and updates installed.
after 3 restarts and system updating messages, it booted and had the yellow bang.
i tried disabling and enabling. i tried rolling back the driver. i tried uninstalling the driver and rescanning for hardware changes.
i tried stopping windows update service and deleting the software distribution folder, so all of the updates could be re-downloaded.
tried it with and without the keyboard.
finally, shut it down, went and did some stuff for 45 minutes, turned it on and no more yellow bang on the sytem aggregate firmware.
so. maybe leaving shut down for a while helps.
I had a number of problems after the update--especially inability to start screen after sleep--I did a system restore which I assumed got rid of all the updates--that fixed the re-start problem--but now it also knocked my wedge mouse out--cannot be recognized--anyone have a solution to that issue? tx
I have downloaded and installed all of the updates, to include the Firmware update. When I look at Device Manager, I see the yellow caution flag under Firmware. Specifically the "Surface Pro System Aggregator Firmware" is flagged. The General tab states that "This device cannot start" .
A quick look at update history shows that this update failed. Have uninstalled, restarted, etc. no solution.
Any ideas?

meant for this to be in the above post. Sorry type cover is to blame, or maybe the operator and not having had enough coffee yet?
After I clicked finish it reset the Surface and gave me a b lack screen saying SURFACE under that "Please wait while we apply a system update." Then the unit rebooted and I was good to go.