Try removing the battery and after disconnecting the power adapter from the wall, try and press the power button for 30 seconds. Leave as is for at least 10 minutes before reconnecting the battery and try powering up. I've been looking at disassembly videos of the unit and since it has one single ribbon cable(outside of the touchpad) that essentially also has the wiring for the keyboard and the power button, it's possible that the ribbon cable itself is damaged.
In the event of the latter, you will need to contact the seller(if it's within warranty period) or take it to a certified technician.