MacBook Pro battery draining while in shut down.

My guess is the battery is at end of life or there is an internal short circuit.

What is remaining capacity?

https://www.macbookproslow.com/how-to-check-battery-health/

Are you certain the laptop completely powered off? I have seen a lot of computers get stuck when shutting down. I find it useful to press the Caps Lock key so the Caps Lock LED is lit, then I select Shutdown from the menu. When the Caps Lock LED goes out, the laptop should be fully powered off. I'm assuming you mean you select the Shutdown option instead of Sleep or closing the lid, otherwise the laptop is still powered on & may perform certain operations during its "sleep" phase.

You have to be extremely careful with the USB-C Apple laptops, since pressing any key on the keyboard or even pressing the Trackpad can power on the laptop. Unfortunately there is no way to disable this "feature".

Do you connect or disconnect anything from the laptop after you have powered it off? If so, then maybe that is triggering the laptop to power on. Closing & opening the display will also power the laptop on. In some cases you can may trigger a power on if the laptop is moved onto or off of a metallic or magnetized surface since you may be triggering the lid sensor making the laptop think it is Ok to power on.

Try disconnecting all external devices from the laptop before you power it off just in case one of those devices is somehow triggering the laptop to power back on.

HTCMark Said:

"MacBook Pro battery draining while in shut down.: I have a MacBook Pro 2019 with i7. When I shut it down, with all applications closed, it completely drains of power. For example, I shut it down at 4:30pm last night and went to power it up at 8am this morning and the battery was at 0%. Any thoughts? I don't see how it is using power if it is off."

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I Had this Issue Today myself. My 2018MBP's battery was down to 1% when I opened the lid --logging in, it was at 76%. No issues since logging in and powering it back off.

TheLittles wrote:

HTCMark Said:

"MacBook Pro battery draining while in shut down.: I have a MacBook Pro 2019 with i7. When I shut it down, with all applications closed, it completely drains of power. For example, I shut it down at 4:30pm last night and went to power it up at 8am this morning and the battery was at 0%. Any thoughts? I don't see how it is using power if it is off."

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I Had this Issue Today myself. My 2018MBP's battery was down to 1% when I opened the lid --logging in, it was at 76%. No issues since logging in and powering it back off.

Actually that is a good point which I forgot to mention. The battery charge level listed on the login screen is not accurate since it doesn't have permission to access updated information with the tightened macOS security settings. The battery charge level must only be checked after logging into a macOS user account. Keeping in mind that the battery could easily charge 10% by the time you reach the Desktop.