Hi,
It can be an issue with the AC adapter itself. But please do try these steps that may help.
- Remove the battery and AC adapter then press and hold the power button for 20 seconds. Plug just the charger and power it on. Once it's on plug the battery in and see if it will charge normally.
- Do test the AC adapter using a multi meter and see if it's giving enough voltage to power and charger the laptop.
- Lastly, try another AC adapter and see if the same problem will persist.