w520 wont turn on with battery attached

[moeghs]

I have been trying to trouble shoot my w520 for several weeks with no luck so far and i dont know where else I can ask my question. I bought my computer from ebay around july of 2017 and it has been great until now.
My specs:
i7 2720qm
nvidia 2000m
8gb of ram
250gb mSATA ssd
500gb hdd
windows 10 os

The problem is that my computer wont run on battery only it has to be connected to my ac adapter. To put it simply battery only = wont turn on, battery + power cord = wont turn on, power cord only = will turn on. So naturally i thought i had a battery problem so I bought two, i repeat 2, genuine looking bateries from amazon and both of them did not work and i ended up returning them because I thought they were not genuine. Now my third battery i bought directly from lenovo's website and it still wont run my thinkpad on battery only. I also replaced my cmos battery but still the same situation. Now my question, is my motherboard bad? Or is there anything else I can do?

thank you for your time reading this

[MikalE]

Sounds like the charging circuit might be bad.

Have you tried installing the battery while it is running on the mains alone? If so, what happens?

Who is the seller on e-bay so I can investigate and avoid if neccessary?

[moeghs]

when the computer is running with the cable i would insert the battery and it recognizes that the battery is there and it gives me a percentage of how much it is charged. If i were to unplug the ac cord the computer shuts off right away like if the battery was never there.

[BillMorrow]

hello and welcome to the forum..

this issue SOUNDS LIKE the same issue i have/had with one of two T61p WUXGA thinkpads..
i don't recall the exact issue but you might need a new system board..
don't go buying one on just my word, wait for a few more opinions..