Hi Forster,
Thank you for posting your problem, I am here to help you today. Possible cause of this problem is due to overheating, software glitches, or hardware issues like a failing power supply or battery
I need to get some information regarding your issue:
What is your Surface Laptop model?
For the meantime follow this steps check if this will help:
Disconnect all device connected to your Surface Laptop and leave the Charger connected only. Restart your Surface Laptop check if any changes.
Let me know how this goes. Looking forward to helping you out. If you need more help please feel free to let me know.
Best regards,
Jansher