I have the same problem. The difficulty is there is no generally available documentation to use to troubleshoot the problem. I have tried a few things but I don't have "THE" answer. I will share what I do know.
The computer was plugged to the charger and used only occasionally for about 12 months. After that, when I turned it on, it would not power up. It was in a stable place and was not moved for a couple of months before I attempted to turn it on. I tried the usual stuff when it would not turn on but it didn't respond.
Because I really like this computer and I cannot afford a new one, I need to "repair" it if possible. I found a motherboard which I bought for only a few dollars, but it was also dead! Caveat emptor! (Sp?)
I examined the board and found several surface-mount fuses. They all checked good. I carefully examined the wires, board traces, etc., but did not see any obvious problem. I plugged in the ac adapter and traced the voltage with a voltmeter, as far as I could, without knowing where it went, or which parts were power supply parts. I was not able to find any lower voltages, so I concluded that the power supply was not operating. That doesn't prove the power supply is the problem-if the problem is in the "on/off" switching for example that will prevent supply from turning on.
Without documentation to further troubleshoot with, I am stuck with just "guessing" and checking to see if I guessed right! I will continue to try. I am an electrical engineer, and prior to that I repaired consumer electronics for several years, so I can guess with a little bit of skill, but it is still guessing. If I find anything, I will make and post a guide here, but I will put the answer here first, as it will take me a while to do the guide. I have been ill for several years so I am pretty slow! But I'll certainly share what I discover (if anything).