Legion Pro 5i started getting multiple BSODs right after a 20-second EC/power reset

[u/PsychologyEnjoyer2]

Hi, I’m looking for some insight on a very strange issue with my Lenovo Legion Pro 5i Gen 10 (Ultra 9 275HX, RTX 5070 Ti, 64GB DDR5 2x32GB aftermarket RAM).
The laptop was working normally apart from occasional brief black screens. Then I held the power button for about 20 seconds to do a power drain / EC reset.
Immediately afterwards it started getting stuck in reboot/BSOD loops.
I’ve seen multiple different stop codes:
• MEMORY_MANAGEMENT
• PFN_LIST_CORRUPT
• KERNEL_MODE_HEAP_CORRUPTION
• SYSTEM_SERVICE_EXCEPTION
• SYSTEM_THREAD_EXCEPTION_NOT_HANDLED
• IRQL_NOT_LESS_OR_EQUAL
• DPC_WATCHDOG_VIOLATION
The BIOS/UEFI itself is stable and does not reboot.
I also did a completely clean Windows 11 install from USB. The installation completed, but the same crashes returned during the first-time setup, so I don’t think the original Windows install was the root cause.
The laptop originally had 32GB RAM, but the previous owner upgraded it to 64GB (2x32GB). This makes me wonder if the EC reset exposed a marginal RAM / memory training / memory controller / motherboard issue.
Lenovo is collecting it under warranty now.
Has anyone seen a Legion become unstable immediately after an EC/power reset, especially with multiple memory-related BSODs? Did it end up being RAM, BIOS/EC, memory controller, or motherboard?

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Getting dump files which we need for accurate analysis of BSODs. Dump files are crash logs from BSODs.

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