NVIDIA dGPU disappeared from PCI/ePSA after s2idle resume, Xid 79 on Dell XPS 15 9500

I am looking for advice on whether there is any remaining recovery path for a missing NVIDIA dGPU, or whether this is probably motherboard-level failure.

System:

- Dell XPS 15 9500
- BIOS 1.40.0, dated 2025-11-26
- Fedora Linux 44
- NVIDIA dGPU expected: GTX 1650 Ti / Max-Q family
- NVIDIA PCI ID before failure: `10de:1f95`
- Intel iGPU still works: `8086:9bc4`

The GPU was working before Apr 23, 2026. The laptop then went through a Linux `s2idle` suspend/resume. On resume, the logs showed NVIDIA ACPI/power-event errors, then around 90 seconds later:

```text
NVRM: Xid (PCI:0000:01:00): 79, pid=6990, name=chrome, GPU has fallen off the bus.
NVRM: GPU 0000:01:00.0: GPU has fallen off the bus.
NVRM: Xid (PCI:0000:01:00): 154, GPU recovery action changed from 0x0 (None) to 0x2 (Node Reboot Required)
```

Before this happened, Linux saw the GPU like this:

```text
pci 0000:00:01.0: [8086:1901] PCIe Root Port
pci 0000:00:01.0: PCI bridge to [bus 01]
pci 0000:01:00.0: [10de:1f95] NVIDIA PCIe Endpoint
ACPI: video: Video Device [PEGP]
```

After powering off and booting again, the NVIDIA GPU was gone. More importantly, the CPU PEG root port `0000:00:01.0` was also gone. Bus `01` is now assigned to an NVMe SSD instead:

```text
pci 0000:00:1b.0: PCI bridge to [bus 01]
pci 0000:01:00.0: [1179:0116] NVMe PCIe Endpoint
ACPI: video: Video Device [GFX0]
```

Current Linux state:

- No NVIDIA device in `lspci`
- No `10de` device
- No `/dev/nvidia*`
- Only Intel graphics appears in `/dev/dri`
- NVIDIA packages are installed
- Secure Boot is disabled
- This does not look like a normal driver issue because the PCI device itself is missing

I also ran Dell preboot/ePSA diagnostics and checked System Information. The VIDEO section only showed Intel graphics:

```text
Vendor Id: 8086
Device Id: 9BC4
Product Name: Intel(R) Graphics Controller
```

I did not see NVIDIA / `10DE` anywhere in the ePSA System Info page. I also tried poweroff/reboot and a Dell flea-power/CMOS-style reset, but the GPU did not come back.

One extra oddity: ePSA repeatedly reports this thermal error:

```text
Thermal: The (SKIN) reading (128C) exceeds the thermal limit
```

I do not know whether that is related, but it makes me wonder if the embedded controller or a board sensor is involved.

My current understanding is that Linux suspend/resume likely triggered the failure, but the dGPU is now missing below the OS. Since Dell ePSA also does not show it, I am worried the issue is motherboard/dGPU/power-rail related.

Questions:

1. Has anyone seen an XPS 15 9500 lose its NVIDIA dGPU completely after Linux suspend/resume?
2. If the GPU is missing from both Linux `lspci` and Dell ePSA System Info, is there any realistic software/firmware fix left?
3. Could the `SKIN` sensor reading `128C` cause Dell firmware/EC to suppress the NVIDIA GPU?
4. Is there any deeper EC/RTC/NVRAM reset procedure for this model?
5. Would BIOS reflashing/downgrading be worth trying, or is this likely a board replacement situation?

I do not know where to go from here. I am trying to avoid replacing the motherboard if there is still a plausible firmware/EC recovery step, but I also do not want to waste time reinstalling Linux or NVIDIA drivers if the GPU is not even being enumerated.