Dell latitude E5570 doesn't turn on correctly

Hi!

I have a Latitude E5570 laptop, which worked perfectly yesterday. This morning, it won't turn on correctly.

I tried (something like 20 times) to remove the battery and the cable, then press power button for a long time (even more than 2 minutes), then plug the battery or/and the cable again, and always the same results:

> When I connect only the cable, with or without the battery, I got a white led for a second for battery indicator

> When I connect only the battery, I got nothing.

When I try to power on again (with battery and/or cable), I got always a white solid led for power indicator, I can hear some very light noise, but nothing appear on the screen, and the keyboard lights on when I press a key. If I press again the power button, the fan go on for 3-4 seconds, then the computer stops.

I tried to remove and replace the RAM and the CMOS battery, to plug an extra screen, and press fn or F12 repeatidily, without any result.

Can you help me?