It sounds like your laptop is overheating. The first thing to test is making sure that your fan is working. If you don't hear it and can't feel any airflow from the exhaust vent, then either your fan or your laptop's fan controller (which is located on the motherboard) is broken. If your fan is working, then the thermal paste between the CPU and the heatsink likely isn't transferring heat properly. Fixing this will require disassembling your laptop and applying new thermal paste. I recommend Arctic Silver 5 or Noctua NT-H1 thermal paste.
There are a few things which could cause this issue. The most likely cause is a broken keyboard, which will need to be replaced. Another possibility is that the ribbon cable connecting the keyboard to the motherboard is making an incomplete connection. Re-connecting it may fix the issue. Finally, the least-likely possibility is that there's a problem with your motherboard.