I am having a very similar issue. It started with the laptop not wanting to turn on by pressing the power button once (with steady orange light) while connected to the charger. I held the power button for about 5-10 seconds and the button light (orange) extinguished, and since then I have not been able to turn on the laptop. I have disassembled the laptop all the way and tested the battery with another same laptop I have and the battery charges properly. I did found that it looks like the motherboard or what the repair manual calls it the system board is not getting any power as I tried the other laptop system board and it works with the broken laptop battery. I hope I don't have to replace the motherboard, because it has the CPU integrated (soldered) in it thus it may be cost prohibited to get a replacement of it. I am gonna try the Lenovo button underneath the laptop and see if that works somehow.