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Turned out to be the trackpad. Cleaned up some corrosion on the keyboard connector and reflashed the original EFI back and it's now booting up just fine. ASD passes. Thanks for your help anyway.

Cheers, I'll give them a try. I just tried one that Duke uploaded in this thread: https://www.rossmanngroup.com/boards/forum/board-repair-troubleshooting/4153-820-3208-bios He forgot to clear the password but the ME region was clean. I removed the password and I still have the same issue. But...

I don't have a donor board for this model. Are you saying that you think the ME region may be what is causing this behaviour? If so, I could clean the ME region.

I had a hard time finding one for this model. Found one on the internet and flashed it, same issue remains. I can't be sure this is a good BIOS image though.

Hi, I have a liquid damage logic board. One of the RAM chips was badly corroded so I reballed it. The macbook will boot and pass ASD EFI but if I try to boot any OS, either ASD or a USB test drive it just cuts out. Any ideas where to start? Cheers, Alex

I ran the USB device presence test in ASD for USB2 and USB3 devices (flash drives) and it passed. It won't boot from my USB2 2.5" SSD however.

yeah it works on both ports with USB2 flash drives. L4600 has continuity about 3.4 ohms. I'm assuming U4600 is working due to the 5V being present and the U4650 mux since it is working with my flash drives but do you think I should try changing those in case they are only partially functioning?

0.64V on both P and N measured at L4600 I have been using the SSD with a USB2 cable.

With wifi card plugged in I get 3.3V and 5V. My SSD USB draws around 300mA at the highest I have seen on my USB meter and the voltage stays at 5V. I just noticed that there is long screw damage on the heatsink screw for U1100. It's the one between the RAM and U1100. Considering the USB comes...

Hi, I have a board that will boot from ASD flash drives but it won't boot from my USB 2.5" SSD macOS test drive. The other problem is that when the wifi card is connected, it won't boot. I'm guessing it's to do with the BT side. Tried with a known good card. I also noticed that the USB...

Hi Paul, That is a killer feature, thanks for letting me know. Unfortunately, I don't have any of those as donors but I have an 820-00840 donor on its way from China so I may just have to wait until that arrives before I can start troubleshooting this job.

Hi, I have an 820-00840-A that had a liquid spill. Q7900 is blown, it is a TI CSD58889Q3D according to the schematic. I can't even find a datasheet for that part#, does anyone know where I can source some of these or something equivalent. A datasheet would be nice. Pins 1 and 2 are shorted to...

Hi Duke, it sprung to life while I was probing it with the CRO probe... PP5V_S4 and all the other rails are now present. I'm sure the problem is related to U7650 but visually it looks fine. I'm going to reflow it with some flux and a bit of solder just incase. I really don't like situations like...

Yeah, I'm getting a really short pulse every ~4 seconds.

Hi Duke, U1900 area looks good. U1900 32KHz is present on pin 10 checked with scope. PP3V1_RTC = 3.08V I took photos of the board before cleaning. Saved them to google drive here: https://drive.google.com/file/d/1uiVSqKi5rLoeHLZWtXaafn71gdXTvMkq/view?usp=sharing...

Hi, I have a board here that won't power on after a liquid spill. U7650 and Q7660 were badly corroded so I have replaced them. After cleaning the board in the ultrasonic cleaner, the rest of the board looks OK. It's missing PP5V_S4. I'm testing using an original Apple 87W USB type C charger and...

Thanks Duke :)

Please let me know if I left out some important info.

Hi guys, I have an 820-00928-A with a 0.5R short to ground on PPBUS_G3H.I removed F7000 and F7001, the short is on the pin2 side. I injected voltage into the pad of where pin2 of F7000 goes and wound up the voltage. It was drawing ~4A at 1.8V and the only thing warming up is the CPU. I'm...

Just in case anyone else reads this thread with the same original question that I had. The 820-00281 schematic and board view are the closest things I could find that is similar enough to be useful for troubleshooting.