Most simple thing to do first i knowbit may not be the cause but some systems i have done was due to ram or hard drive.
Try trying one by one. If your systems has 2 memory slots remove the top ram stick then try to power on. If no luck then swap the 2nd slot with the one you removed. You may only have one port if so remove the ram and the hard drive and see if it will power on if it does you should recieve a beep. If not try putting the ram in first - power on. Then try just the hd - power on.
It could also be an over heated board. Maybe try stripping the system down, remove the heat sink and re apply some new paste. Otherwise yes you could have a faulty board.
Though may i ask... Have you tried with a genuine acer charger both yiurs and a 2nd for testing. As i know alot of dells have issues with a non genujne charger.
Hope a bit of my advice can help, if not then sorry. Good luck