Green dots and screen freezes

Your Lenovo IdeaPad 3-15IIL05 displaying green dots and freezing after a period of use, especially after a low voltage incident and a previous motherboard repair, points strongly towards a GPU (Graphics Processing Unit) or VRAM (Video RAM) issue. The fact that an external display doesn't work is a critical piece of information that almost confirms the problem is with the integrated graphics on the motherboard.

Here's a detailed breakdown of what's likely happening and why:

The Intel Core i3-1005G1 processor in your laptop has an integrated GPU (Intel UHD Graphics). Unlike dedicated graphics cards, this GPU is a part of the main processor chip, which is soldered directly onto the motherboard.

1. Low Voltage Incident: A low voltage or power surge event can cause microscopic damage to delicate electronic components. While a previous repair might have fixed a different part of the motherboard, the GPU or its surrounding components (like the power delivery system) could have been weakened.
2. Symptoms of a Failing GPU:
   • Green Dots (or other artifacting): These are classic signs of a failing or corrupted GPU. The GPU is unable to correctly process and render the image data, leading to random colored pixels or patterns on the screen.
   • Screen Freezing: This occurs when the GPU freezes or crashes, stopping the display from updating. The system itself might still be running in the background, but the graphics output is stalled.
   • External Display Not Working: The GPU is responsible for sending video signals to both the internal display and any external ports (like HDMI). If the GPU has failed, it cannot send a signal to either, which is why your external monitor remains blank.
3. The "Barely Starts" Behavior: The fact that the laptop sometimes boots for a few minutes before the problem starts could be due to a thermal issue. When the laptop is cold, the GPU might function for a short period. As it heats up during operation, a faulty component (like a weakened solder joint on the GPU itself) expands and loses connection, causing the graphics to fail. This is a common pattern for "cold boot" issues in electronics.

The motherboard repair you had two months ago might have fixed a different component that was initially preventing the laptop from turning on. For example, it might have been a power management chip (PU) or a power delivery circuit (VRM). However, the underlying damage to the GPU may have been present but not immediately apparent. The stress of normal use eventually caused the weakened GPU to fail completely.

Given the symptoms and the history of the device, the only reliable solution is a motherboard replacement.

• GPU is on the Motherboard: Since the graphics are integrated into the CPU, which is soldered to the motherboard, the entire board needs to be replaced. Repairing a BGA (Ball Grid Array) component like a CPU/GPU is extremely difficult and often not cost-effective or reliable for consumer-grade laptops.
• The Repair Shop's Role: You should take it back to the repair shop that did the previous work and explain the new symptoms. They might be able to offer a solution or a discount on a replacement, especially since the problem reoccurred so soon after the last repair.

When you take your laptop in, be very specific about the symptoms:

• "The laptop freezes and shows green dots on the screen after a few minutes of use."
• "This happened after a low voltage incident, and the motherboard was previously repaired."
• "An external display does not work."

This information will help them quickly diagnose the issue as a GPU failure and provide an accurate assessment of the repair options. Unfortunately, with the GPU being integrated, a full motherboard swap is the most likely and permanent fix.