Chosen Solution
I replaced the battery in my mid-2009 MacBook Pro and the now the battery icon in the upper right-hand corner of the screen has an X in it. It doesn’t always happen though. It seems to happen after the laptop has been fully charged and remains plugged in. It’s like it only happens when its been charging for a long time, like its a reaction to being over charged. When it’s in this state it won’t turn on without being plugged in. I haven’t quite figured out how it gets out of this state but occasionally it does. This last time, I popped off the back cover of the laptop and unplugged the battery-to-logic board connector and reseated it and then popped the cover back on. Now the computer works fine when not plugged in and my battery is at 100%. I don’t know if this is helpful but this is the info from the System Profiler when the battery reads 88%: Charge Information: Charge Remaining (mAh): 5408 Fully Charged: No Charging: No Full Charge Capacity (mAh): 5912 Health Information: Cycle Count: 5 Condition: Normal Battery Installed: Yes Amperage (mA): -1247 Voltage (mV): 12048 I find the Amperage being negative odd… Any body else have this problem? Did I get a bad replacement battery?
So iFix it sent me a replacement and the problem went away. :)
I just had this happen after installing a new battery. I had nicked this cable: https://www.powerbookmedic.com/MacBook-P… its very fragile and right next to the battery connection to the motherboard. It also would not fall asleep on close.
