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.
Checked for corrosion around U1900 - none visible. Replaced U1900 anyway from a donor board but same - still got cpu vcore but no chime/display. As for activity on USB - nothing at all with USB mouse or keyboard - if I plug a USB flash drive with a light on it though it does light up for a few...
Ok this one has gotten me completely stumped. Initially the macbook came in with water damage and the keyboard wasnt working. Opened it up and found Pin 4 of J4813 was burned away also some corrosion around Q7520. Replaced J4813 and cleaned up the area around Q7520 - turned on got to the boot...