HP Probook 450 G5 won't turn on and there are no lights

[Ajo7]

My father used this laptop when the screen went black. There was no ac adapter connected only an external hdd and a wireless mouse usb connector. 
I unplugged everything then connected the ac adapter but there are no lights next to the adapter. Then i unplugged the ac adapter from the laptop to try reseting it by holding down the power button (I can't remove the battery) and plugged back the ac adapter, but it doesn't work. Tried multiple times. There are no damage on the ac adapter or on the laptop. It's a new laptop about 2 weeks old. We bought a Solid-state Drive (SSD) Samsung 970 EVO, 250GB, PCI Express, M.2 in it, but it worked well. The laptop was resealed, but there was nothing wrong with it when we bought it, only the hdd was not placed well and we had to reconnect it. 
Please can someone help me?

[WAWood]

@Ajo7 

You paid for free HP Tech Support as part of the warranty coverage, so you might as well make use of it.
While this PC is still under warranty, you should contact HP Customer Support directly to have them put you in touch with HP Technical Support to see what they can do about troubleshooting and repairing your machine remotely.

If they can't repair it, then you should explore options for getting it replaced under warranty.

If you live in the US or Canada, contact information is on this page: http://www8.hp.com/us/en/contact-hp/phone-assist.html#section1
If you live elsewhere, contact information is on this page: http://www8.hp.com/us/en/contact-hp/ww-contact-us.html
NOTE: After you get through, stay on the line until you are finally able to talk to some one -- it can take a while!
If you have trouble finding a phone number, then try: 1 (800) 474-6836

[Ajo7]

Ok thank you!

[Ajo7]

I left plugged in the computer the whole night and now it can start, but the sceern is black. I don't think the RAM is the problem, because it doesn't die, but the screen won't turn on. I connected a different monitor, but it does not show anything.

[WAWood]

OK ... but we can't fix it or troubleshoot it from here.

As I mentioned, you need to contact HP Customer Support to then get in touch with HP Tech Support.