My computer wont boot up

I got an ASUS, power supply: SFC sf-630p12p 630w,video card:zotac gtx 760 2gb 256bit ddr5, motherboard: foxconn 115xdbp, internal drive:seagate barracuda 500gb (didn't know what was necessary so wrote down what I know)
When i start up the computer evrythings seems to start up my keyboard, my mouse the fans and one of the lights on the harddrive. but my screen keeps saying no signal. i have tried multiple keyboard combinations, different screens,CD didn't help and windows online support wasn't that great, all I believe I have left is to open it up but with no experience in this I whould like some help lika a step by step guide if that's what needed. This all started one day surfing the web when suddenly it shouts down and the screen says downloading files for windows 10 I believe that I have had an information about windows 10 in the corner where it said ``do it in 30minutes´´ or so and I just closed it where i belive the timer went on. after that when it suddenly happend and it had done evrything it wanted it said the computer will restart and after that the screen didn't have any signal. Evrything that happens now when i turn it on is that one flashing light flashes in different combinations until after aout 20minutes being on and it ends. Have had this trouble for a while and now I am reaching out for someones help! I'll be glad for any answer I'll get