15 R3, 2 red 3 blue blinking code, problem

Last year my computer ran into this problem: the power button just blinks red twice and blue three times with no alarm sound and the screen is totally black, but the LED light seems to work just fine. I was out of my warranty so I looked up blink codes and opened it up and replaced the RAM but it still didn't work, so I just assumed the problem was with the motherboard.

Oddly is, I was able to turn it on after 48h or so, and it works perfectly when I play games. But I can't turn off or restart the computer, otherwise, the computer would just go blink again. Sleep mode, however, has no effect at all. So for a while, I didn't shut the computer down. Since I bought the computer from China and I'm currently in Europe, I've decided to take it back and repair it. At Christmas, I took it back and sent it to the repair but they told me it worked just fine, with no hardware problems whatsoever, except for the bulging battery so they unplugged the battery wire.

They suggested me to reinstall the operating system and it worked for like half a month and it's happening again. 4 days ago it went back to the blinking code statues and 2 days ago, I was able to turn it on again, so I reinstalled the system completely, and the first reboot was successful but the second one brought it back to blinking, now it seems like it's depending on luck.

I've tried pressing the power button for one minute thing, I've tried to fix and detect problems with Dell support software when the computer was able to work and nothing really works. Any suggestions or anyone who has seen this problem before? Thanks.