Hi DevashishFx,
Welcome to Microsoft Community.
I'm sorry to hear that you're experiencing issues with your Microsoft Surface Laptop 4. Overheating and frequent restarts can be caused by a variety of factors, including a faulty battery or charging port. Since you've already tried resetting the laptop and charging through the USB-C port, it's possible that the issue is hardware-related.
The post-service warranty is 90 days or the remainder of the warranty, whichever is greater. If your device was outside of the Limited Warranty, you'll get a 90 day service warranty. However, before sending your device in for repair, I would recommend trying the following troubleshooting steps:Run the Surface Diagnostic Toolkit: Fix common Surface problems using the Surface app and Surface Diagnostic Toolkit - Microsoft Support Memory dump files can be very useful if you are experiencing Windows blue screen problems and want to learn more about the specific errors that are causing these crashes. These files store detailed information about the error and can help you identify the root cause. Windows keeps a list of all the small memory dump files in the %SystemRoot%\Minidump folder. You might consider sharing the details of the error here and I can help you analyze the information or provide more guidance on how to fix the problem.
If none of these steps resolve the issue, then it's likely that the issue is hardware-related and you may need to send your device in for repair. You can process a repair order online or contact Microsoft support for further assistance. Your SincerelyHahn. W - MSFT | Microsoft Community Support Specialist