Laptop won't turn on

I have a Dell Inspiron 15-3552 laptop that won’t turn on. Several nights ago I used it and it worked fine.

Here’s the problem. When I press the power button nothing happens. Wait a couple of seconds, press the power button again and the power light comes on for a couple of seconds and then starts to dim until it goes out. Anyone know why. Thanks.

Was this on a fully charged battery or PSU?
If it was PSU, do you have another PSU you can try?
Unless another PSU can get it running, it is going to require professional diagnostics.