Hi Maddy,
I am Dave, I will help you with this.
You indicated you have pressed the power button for 30 seconds, please try this method.
Disconnect the power cable, and if the battery is removable, remove it
Press and hold the power button on the case of your laptop for 30 seconds
Wait 30 minutes.
Then reconnect the power cable and battery if you disconnected it
Try starting the laptop again, does anything appear on the screen?