Hi, thanks for accepting me on this forum, I'm an Italian maxcomputerlab repairer, I'm repairing a 16-inch MacBook a2141 without backlighting. I replaced the entire series of capacitors from q8460 to q8473 without obtaining results with the board disassembled on the bench. I noticed that the 12s come out of the F8400 fuse. ,6v enter R8400 pass and enter Q8400 but then do not exit from pin 6 of Q8400 I am thinking that the problem is the u8400 controller which does not give consent? Can you help me solve the problem? Thank you