My Lenovo Legion Y540 was working normally before I took it in for a keyboard replacement because of water damage. Since the repair, it boots into Windows and reaches the lock screen, but powers off after about 1–3 minutes. The repair shop suspects overheating or a thermal-sensor problem. The fans are connected, and they even tried replacing both fans without changing the behavior. When the laptop is completely cold, it lasts a few minutes; if they turn it on again while it is still warm, it shuts down almost immediately. What could have been disturbed or left out during the keyboard repair?
3 Answers
The first things I’d check are the heatsink assembly, thermal paste, and every thermal-sensor connection—not just the fans. During a keyboard replacement, the cooling assembly may have been removed or shifted. If the heatsink isn’t making proper contact with the CPU or GPU, or the paste was damaged and not replaced, the system can reach its shutdown temperature very quickly. A disconnected or damaged temperature-sensor cable could cause the same protection behavior.
I’d have the repair shop reopen it and document the temperatures and sensor readings before doing more part swaps. They should verify that the CPU/GPU heatsink is mounted evenly, the correct screws and brackets are installed, thermal pads are in their original locations, and no sensor or fan cable was pinched during reassembly. The timing makes a heat-transfer or thermal-monitoring fault much more plausible than a normal software crash.
Try booting from a known-good live USB environment. If it also shuts down there, that points strongly to hardware rather than Windows or a driver. Since it behaves differently when cold versus warm, though, a cooling or sensor problem is more likely than an operating-system issue.
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