Power Problems with a Emachines W2040

Ok. Here is the situation. A few weeks ago my emachines pc began not acting right. For one thing it would not keep time. The second thing, I came in one day and my PS2 keyboard was not working. The lights on the keyboard were rapidly flashing back and forth. I bought another PS2 keyboard and it wouldnt work either. I figured the PS2 port was bad, so I bought a USB keyboard and plugged that in and it worked just fine. I also at this point used my restore discs because I thought that I was having problems with Windows so I wanted to reinstall it. Well the PC worked fine for about a week. I come to get on it one morning and the lights on the BRAND NEW keyboard are flashing and guess what? They keyboard wont work again. Well I cut the pc off and turned it back on and when I did, it failed to come on at all, and I could smell burnt wiring coming out of the power supply. I changed the power supply out and now the pc would come on, The hard drive light came on, the disk drives were working but I never could get ANYTHING to come up on the screen. I thought maybe the problem was with the CMOS battery so I bought one and put it in, and now it wont do anything. It wont power up or anything. Does anyone out there have any suggestions as to what to do, or is this a lost cause, did I in some way fry the mother board for this pc or is there some reset I need to do. I know this PC is 6 years old, but I would like to salvage it if possible.