For $29/mo, we provide access to advanced level technicians who will answer your questions on any Macbook board related matter to the best of their knowledge promptly & walk you through how to solve your problem so you can deliver a working board to your customer.
2850 has "ignition" version of ME. So you need to find a clean "ignition" version, I believe only 150KB. I bet it is quicker to swap a PCH+BIOS from a donor board.