Can't open, despite clicking power button.

@adarshgautam start with the basics. First you want to check your power supply. Make sure it has the proper voltages. Check to make sure the connectors are not bend etc. After that, check the phones charging port. Clean it of any debris etc, use a few puffs of air to clean it out. If none of this works, get an ammeter and see if your laptop draws any amperage from the charger. After that, you need to check and see if your motherboard even gets power. For that of course, you need to open it up.

Since iFixit doesn't yet have a guide for that, you want to use something like this video to work on it. The issue could be your charging port or, a failure on the main board. You would need to measure the solder side of the charging port and see what the voltage is when you connect your charger. Look for anything "odd" damaged, or missing components on your main board. If in doubt, you can always post pictures of what you find with your Question. Adding images to an existing question

Repair is War on Entropy!