Nikon D5 – dead, power board issue ?

[corrize]

Hello, the DSLR has heavyly fallen. It is dead : no sign of life and display nothing.

When it worked, it always displayed a card present state on LCD display, even when the battery is empty it display a empty battery symbol.
I found a dead fuse, I replaced it and a mosfet burnt, I changed it and another fuse burned. Nothing burned after. And I can't find any short circuit anywhere, it's weird.

Now, I try to understand how it works.

There is two boards (the little one on pictures has no component) : the first is a « power board » : managing the battery and create voltages from 12v battery with switching power supply (3.3v, 5v and another).
And the second board (the big one) is the motherboard.

Measurments :

Board 1 (power board) :
Battery 12v is present but all coils at outputs of power chips are 0V. There is a chip, a step down DC-DC converter TPS54341 (0v at outputs coils) but the pin EN : 0v, so it is not enabled.
500mV in diode mode at coils.

There is another chip : a PMU (ADP5080)
https://pdf1.alldatasheet.com/datash...D/ADP5080.html
This chip manage battery and battery state (not the charge, the DSLR can be charged only with external charger), it has buck regulators, LDO, provide 3.3v and 5v and I2C.

I can't measure it because it's a BGA chip, but all VIN (12v) are good, I measured 3.3v and 5v at the little resistors close but not at coils, all coils are 0v. So it don't « provide » 3.3v and 5v. The coils are around : 900 Ohms, 2k, 10k, 20k and around 100mV in diode mode (it is low).

Board 2, motherboard :

The main voltage (battery 12v) is present. I found 5v but only at a one little resistor but not at USB for exemple. I can't find 3.3v anywhere. I can't measure anything at chips ont this board, no voltage at pins. So the processor and other chips are not powered.

So what do you thinks in a logical approach pls ? I don't know how to work this kind of chip (PMU or PMIC), if it's should be always on or not ? Can I suspect it ? (It has a « EN » pin for enable, but I can't check it). I guess this chip should be always on for essentials voltages (3.3v). But the chip is not shorted and that can't explain the fuses burned.
Another way can be an issue in the battery protection but I don't know how it works ?

[corrize]

Re: Nikon D5 – dead, power board issue ?

Update : I connected only the boards with stand by 3.3v (and the top cover with the power on button). And without the motherboard.
And when I press the power button, the screen display goes on.
But it is just the display on, the battery symbol turning in loop and give no information.

After, I connected the motherboard, the battery symbol seems indicate a level stable.
But I noticed the PMIC (ADP5080 or ADP5080ACBZ, see the first post) is burning.
I guess, the PMIC has received the enable signal from motherboard, tried to start but shorted. I saw nothing shorted around this chip (coils, caps), but it is a BGA one, so I can’t measure all pins.

So, if you have experience to PMIC chips, replacing this chip could be solve the issue ?
I would have your advise before replacing this chip because it’s a BGA one and it is expensive. Thanks.