Asus Q400 power problem

For awhile now my laptop has had a lot of trouble powering up and it is getting worse. At first it shut off when we bumped the power cord the wrong way and usually would start back up in a few tries. Now, we're lucky to get it to power up at all. The battery hasn't held a charge so we stopped using it awhile back and just run the laptop off the power cord directly. There is no indication of a faulty transformer so I'm not sure if that's the problem. Sometimes when we twist the male end, that plugs into the laptop, just right it will work. Usually when we try to turn the laptop some of the lights and backlight for the keyboard turn but the screen never lights up. The lights turn on like the laptop is about to work but then it quickly reverts back to only the light bulb light or just turns off all together. What should I do? Computer repair is pretty spendy and I'm pretty broke so I'm kind of at an impasse.