General troubleshooting:

Unplug the AC adapter and disconnect the battery. Hold the power button for 30 sec.  Verify that the LED on the DC end of the adapter is ON -- if it's not, replace the adapter.

Remove the base cover and memory, and reinstall the memory.

Power up on AC only - if it will but won't with the battery installed, the battery is faulty.

If it still won't power up, replace the mainboard.

The system is under warranty, I don' want to open the cover.

You'll need to contact the seller from whom you purchased the system - all support/service is through resellers in your part of the world.