I'm going to try to get a donor board . Thank you so much for your help!

Thanks! I'll remove it then. If the UP700 turns out to be the issue, would you recommend buying a replacement individually (USD $10 on AliExpress or eBay), or getting a scrap board and pulling it from there ($150 on eBay)? What do you think?

Hi all,
I'm a beginner at laptop repair. I bought a MacBook Air A2681 that doesn’t turn on, just for practice. PPBUS_AON and the other always-on voltages are present and look fine. I did some diode mode measurements and got unusual readings (compared to reference values I found online) on LC320 (44mV) and L82D0 (40mV). LC320 corresponds to the PP5V_S2 power rail, and L82D0 to PP1V25_S2.

I injected 1V (current limited to 100mA, the board consumed around 86mA) into PP1V25_S2 to see if anything would heat up, but everything seemed normal. I did the same with 5V (current limited...