Okey thank you I will try that
Did it Turn on without the Batterie connected ?

Update — a lot of measurements since my last post. No short found, and I’m now stuck at interpreting the behavior.

What I measured:

• Diode mode on PPBUS_AON: 0.5 to ground at the tantalum bank and at U5700 VIN, same everywhere. No short found on the rail.

• On a 5V USB 2.0 supply, U5200 boosts PPBUS_AON to a stable ~12.3V and holds it.

• PP3V8_AON stable at 3.8V the whole time.

• DFU mode works: device enumerates, ECID reads, both Apple Configurator and DFU Blaster Pro identify it as Mac14,15.

• Every...

On the 15” board there is no fuse on PPBUS_AON — the charger output cap bank sits directly on the rail, nothing in between. So I can’t isolate the regulator by pulling a fuse. What should I lift instead Or did i miss something? ...

PPBUS_AON is not stable: with the charger connected it ramps up to ~12.3 V, collapses to 0 V and repeats. The light on the magsafe charger flashes orange in sync.

Hi everyone,

I’m new to board level repair, so apologies if I’m missing something obvious.
I have a MacBook Air 15.3” (A2941) that won’t turn on. No keyboard, no trackpad. It does show up in DFU mode using a DFU Blaster Pro. On all ports it power cycles between 5V and 18V.
I’ve attached a video of the cycling and a screenshot of the DFU Message
Any idea where to start looking, or what I should measure first?

Thanks!...