i have a foxconn 15235
That is only the MB details, can you also tell us the brand and model name or number of the power supply, the RAM (including the amount) and any add on video card.
I took of the top cover and pressed the button and the fans would start and stop with each flash.
Too soon to say but a couple of possible causes, a faulty power on button, a bad "power good signal" between the PSU and MB, bad PSU or a loose memory stick or connection.
When you post back, can you also advise as to how comfortable you are with working inside of a PC and of the safety steps that need to be taken before starting.