HP ZBook Fury 15 G7 random hard shutdowns – Kernel-Power 105/521, battery disappears

[Loevee]

Hello,

I am troubleshooting recurring hard power-offs on an HP ZBook Fury 15 G7 Mobile Workstation.

System

• HP ZBook Fury 15 G7
• Windows 11 Pro 25H2
• BIOS: S92 Ver. 01.25.00, 12 June 2026
• 32 GB RAM
• Intel Core i7-10850H
• NVIDIA Quadro T1000 with Max-Q

Main symptom

The laptop randomly powers off instantly while running normal Windows. There is no BSOD or shutdown screen. Event Viewer later records Kernel-Power Event 41 with no bugcheck.

Sometimes after such a shutdown the laptop will not boot normally until I hold the power button for approximately 30 seconds.

At the beginning of the problem I also had one incident where the laptop powered on with fans/lights active but no display, including external display. Caps Lock/Num Lock blinked approximately five times repeatedly. Using the HP Win+B BIOS recovery procedure allowed the laptop to boot again.

Very important: Safe Mode is stable

During the first occurrence of the problem, Windows Safe Mode ran continuously for approximately 6 hours without shutting down, while normal Windows could shut down within seconds or minutes.

HP UEFI diagnostics

I ran HP PC Hardware Diagnostics UEFI:

• System Board: PASS
• Memory: PASS
• Processor: PASS
• CPU stress test (~15 minutes): PASS
• Onboard video: PASS
• AC adapter: PASS
• USB/audio/PCI tests: PASS

The laptop can also remain running inside UEFI diagnostics for a long time without shutting down.

Battery test reports Primary Battery OK / Logic State OK, but Component Test WARNING. Battery has approximately 390 cycles and approximately 69% remaining full-charge capacity.

Windows troubleshooting already performed

I tested:

• clean boot with non-Microsoft services disabled
• startup applications disabled
• NVIDIA GPU disabled
• Intel Wi-Fi disabled
• VPN/Wintun/TAP adapters disabled
• Hyper-V temporarily disabled
• SFC /scannow: no integrity violations
• System Restore
• uninstalling Windows updates

None of these solved the issue.

I then performed Reset this PC → Keep my files → Cloud download.

After the fresh Windows installation, the laptop was completely stable for approximately one week, including WSL2 and Docker Desktop. Then the same hard shutdown problem returned.

Power-related Event Viewer data

While the original HP AC adapter remains physically connected and is not touched, Windows repeatedly records:

Kernel-Power Event 105 – Power source change

Example:

17:45:16 AcOnline=false

17:45:38 AcOnline=true

17:46:50 AcOnline=false

17:47:04 AcOnline=true

17:48:01 AcOnline=false

17:48:15 AcOnline=true

At exactly the same timestamps, Windows records:

Kernel-Power Event 521 – Active battery count change

with:

ValidBatteryCount=0

immediately followed by:

ValidBatteryCount=1

ErrorBatteryCount=0

AbandonedBatteryCount=0

So the Windows power subsystem appears to temporarily lose the battery at the same time that it reports AC power disappearing.

Windows Update

The PC was running Windows 11 25H2 build 26200.9168 with KB5121003.

I uninstalled KB5121003 and verified that it is no longer installed. The build reverted to 26200.8973 and Windows Update is currently paused.

However, the laptop performed another identical hard shutdown approximately 30 minutes later, so KB5121003 does not appear to be the sole cause.

Current test

I am currently testing the laptop completely disconnected from AC power, running only from the internal battery.

My main questions are:

1. Is this combination of Kernel-Power Event 105 (AcOnline false/true) and Event 521 (ValidBatteryCount 0/1) known on the HP ZBook Fury 15 G7?
2. Could this indicate an EC/ACPI/BMS/power-management issue rather than a simple battery failure?
3. Is BIOS S92 01.25.00 the recommended BIOS for this model?
4. Are there specific HP SoftPaq power-management / Intel Management Engine / ACPI drivers that should be installed or rolled back?
5. Considering that Safe Mode remains stable and HP UEFI diagnostics pass, what would be the recommended next diagnostic step?

Thank you.

[Loevee]

Battery-only normal Windows remained stable for several hours.
Safe Mode with the AC adapter connected also remained stable for approximately one hour.
The hard shutdowns currently reproduce only in normal Windows while AC power is connected.