Questions about general OTA update dev cycle

[junkbot]

Hi all,

I tried briefly searching the forums/Google for answers, so I apologize if this has already been answered and I missed it. I'd like clarification on the life-/dev-cycle of an OTA update. From my understanding:

1.) Google's Android team works on a new revision of the Android OS (e.g., 2.3.4)
2.) Google then releases the stable code and the phone manufacturers (e.g., Motorola) picks it up and adds their device specific changes
3.) The phone manufacturer passes this code on to the carrier (e.g., Verizon) for them to add their bits of code.
4.) Verizon pushes out the OTA update once everything has been approved and tested.

Is that correct? And who is technically responsible for the code that gets pushed out? For example, the OTA update bricks a non-rooted, unmodified phone - who is responsible for that, the carrier or the manufacturer, or Google?

Thanks!