Xps13 9360 - doesn't boot - please help me

Dear Dell community,

I sincerely hope you can help me out. In the last weeks my laptop had hard times to boot. Sometimes I had to click a few times to turn it on as the light under the power button was turning on and then off after 2 and sometimes 5 seconds. Eventually it was booting after a few trials. Yesterday, instead, it didn't turn on for like 1 hour when at work so I followed the instructions which I found on this blog in order to solve this issue once for all (

Disconnect the AC adapter.

Disconnect the "Main" battery.

Disconnect the "CMOS/BIOS" battery.

Hold down the power button for 10-15 seconds.

Connect the AC adapter and test. )

However since I did this, the computer seems to be just dead. The laptop hasn't boot since. I repeated the exercise above a few times but nothing. 

Now when I click the power button, the light stays on for 2 seconds and I can hear a tiny micro sound a moment before the light under the power button goes off. Like it s starting but then it doesn't manage to.

Does anyone have any idea on what to do? I am desperate, I bought this first class computer with my savings 3 years ago and I am so disappointed and devastated at the idea that I need to get rid of it already. 

I hope in your help. Fabrizio