In the past week or so, my Lenovo X220 laptop (bought in mid-2011) started to give some power troubles. The first time, it just suddenly turned off completely without any warning (no blue screen, no flicker, no sounds, the screen and all lights went off instantly), although it had battery at near full charge and was also plugged in. On rebooting it stated that the system had not been shut down properly and asked whether I wanted to start Windows in safe mode. I chose to "start normally". The laptop was not hot, and there were no event logs at the time that it turned off. The second time, the laptop was sleeping with nearly full battery and plugged in, and when I came back to it I found that it had turned off spontaneously. Of course, I lost whatever I had been doing on both occasions, but everything else seems to be running fine.
Around the same time, I noticed another weird issue. Sometimes, after shutting down normally and waiting a while after the lights all went off, switching off the power adapter resulted in the laptop making the usual X220 double-beep, which normally indicates that the laptop has been unplugged from the AC supply. What is not normal is that in the past it never did that when the laptop was off. Furthermore, after beeping, the batter light turns on for about 10 seconds before turning off again. Nothing unusual happens when I turn the power adapter on and off again after that.
I did not change the BIOS settings since the beginning, nor did I do any recent updates or install any software. For the second issue, I ruled out the battery and the adapter, because I have two original batteries from different sources and two original adapters from different sources, and the issue still arises regardless of which I use. I never ever dropped or bent the laptop, and it is always placed on a flat surface, and I never opened it or spilled anything on it, or did anything that I can think of that might be related. If the first issue is related to the second, which I think it is, then the only explanations I can find right now on the internet that seems to be likely is that there could be a fault with the power circuit or the CPU.
A third issue that I had since 2011 was that sometimes the laptop would take a while to register that the power supply is connected, and unplugging the power cord and plugging it back into the laptop would make it register immediately. This is probably unrelated since the other two issues occurred at the same time this year, but I thought I should mention everything that was power-related.
I have no idea what to do now.
=== Some Specs === BIOS: LENOVO 8DET46WW (1.16 ), 2011/05/18 OS: Windows 7 Professional SP1 CPU: Intel(R) Core(TM) i5-2520M CPU @ 2.50GHz, 2501 Mhz, 2 Core(s), 4 Logical Processor(s)