View source for All voltages pressent, doesn't boot and there the ACT LED is completely off

{{DISPLAYTITLE:All voltages present, it doesn't boot and the ACT LED stays off}}
{{DISPLAYTITLE:All voltages present, it doesn't boot and the ACT LED stays off}}
{{Repair Guide
|Device=Raspberry Pi
|Affects parts=QSBP K7D
|Needs equipment=Soldering iron, Hot Air station, solder paste, universal stencil.
|Difficulty=3. Hard
|Type=Soldering}}
== Problem description ==
[[File:QSBPK7D.png|thumb|QSBPK7D location on top side]]
All the revisions of the Raspberry Pi 4 have this very tiny chip with marking (QSBP K7D) located either on top between the SoC and the GPIO header or on the bottom side near the SoC underside. 

The chip is in a BGA-6 package with exposed Silicon crystal and it's very easy to mechanically damage it by accident.
== Symptoms ==
* If damaged when you connect the Pi to power, the RED LED will stay on, there will be little to no activity on the GREEN LED and all the voltages from the main PMIC (MXL7704-P4 or DA9090) will be present, but the Pi wouldn't turn on.

== Solution ==
[[File:QSBP K7D.png|thumb|QSBPK7D close-up on the bottom side]]
The only solution is to replace it, with chip from a donor Pi.
As of writing, I haven't been able to identify the chip or find it up for sale.

You would need a universal stencil and solder paste in order to replace the chip!
=== Diagnostic Steps ===

Usually you can see a crack running across the chip when it's damaged.Even a chipped edge or corner is enough to damage it.
[[Category:Raspberry Pi Foundation Others]]
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