Chosen Solution
My MacPro was operating perfectly yesterday, but suddenly today, it show No battery available as the image
I tried to reset SMC, reset NVRAM several times but it still doesn’t work. Whenever I unplug the connector, it will shutdown slowly, then if I press the power button, screen will show the red icon that run out of battery. Edit1: At login screen, I see the battery icon is normal (90%) for 5 or 10 seconds, then it show an “X” icon again Edit 2: When I login as Guest user, unplug, it shutdown, but I can turn it on again by pressing power button, without charging. So what could I do in this situation? Thank you.
Battery is getting power (hence why it works with charger unplugged) but the data line for power has an issue, so it thinks there is no battery disconnected. If you unplug the charger, usually the screen will fade out instead of turning off straight away (when the battery is actually disconnected) and on older models, the fan will still spin for a bit when the charger is unplugged, when it has a data line issue with the battery. This will be a logic board related issue in most cases, sometimes it is battery related on the newer models; check for liquid damage and clean where necessary with 95%+ isopropyl. If you have experience and tools for microsoldering, I can further guide you on points to measure with a multimeter; otherwise, best to send it to a repair centre who specialises in logic board repairs.
