Dell Inspiron 15 will not power up...no video, no fan,

I was using laptop on battery for about an hours, closed it up and put it back on power supply. The wife went to use it later and could not get it to power up. I tried, had same problem. Unplugged power supply, removed battery, held down power button 10 seconds....repeatedly. Nothing except a little blue indicator light on the front of the PC and one very faint sound when power button pressed. Let it sit overnight with power and battery disconnected. Tried again this morning, only the blue light and the fain sound.

While under warranty, Dell replaced the motherboard TWICE. then it gave a series of loud beeps as a code.

Any suggestions, other than not buying a Dell computer.