MBP immediately shuts down when power cable is disconnected

[Glenn812]

My MBP rebooted without a reason, then it started up and rebooted again. Then it showed the login screen, but as soon I typed my password and hit enter, it again rebooted immediately for 2 times. After multiple attempts, it did log in until it was just a second in the Finder, and again was rebooting. I tried to enter the password in the login screen en pressed enter while holding the shift-key and (coincidentally or not) this worked, as I'm logged in for a while.

During my attempts (and plugging off any devices) I also noticed that as soon the power cable unplugged, it immediately shut down. I can't boot the MBP without the power cable plugged anymore. I have reset SMC and PRAM but no progress.

I also noticed it won't startup at all when I the HDMI-cable plugged, for a second monitor. As soon I plug it in when it's up, the MBP reboots and seems to go back in this endless reboot-thing.

The battery is pretty new (5 months, after old one broke), and diagnostics show it's condition is good (just 3 cycles) and nothing appears wrong. (see attachment)

More specific: The very first reboot happened when I played a game (Asphalt8) and switched back to my browser (Epic Browser) with shortcut Command-Tab. As soon it switched, the MBP rebooted (twice, and log in screen after that). I tried to replicate it, and same happened a second time. To avoid breaking things I don't (dare to) replicate it a third time.

Does anybody knows what could be wrong? I leave the MBP plugged all the time and haven't uncharged it since I got the new battery, 5 months ago. MBP is up nearly 24/7.

Thanks already!

 

[maerz001]

Was it from apple installed? Let them do a check

 

[Glenn812]

After my battery died last May, I brought the MBP to the local Mac repair shop. My MBP was suddenly dead, and I had no back-up of my data (stupid but true). This is why I told them to be very careful with the HD and certainly not wipe it. They promised to do so, and send the MBP to their certified repair company. A week later they called me that this firm accidentally DID wipe the entire HD. Lost thousands of hours of work. I have no trust in this company anymore and rather like to know what could be the problem, before sending my MBP to Apple (there's no warranty left). I do suspect it had to do with the battery (replaced by this certified company that wiped my HD, 5 months ago).

I've done a few more tests today. It rebooted once when I had opened multiple applications. Like it's shutting down when things are getting a little heavy. The game I mentioned (Asphalt8) is the only heavy app that will make the MBP reboot immediately as soon I open it. The last 6 hours I just left the MBP idle, and no reboots occurring.

Except when I accidentally touch the "magnetic" power cable, so it disconnects from the MBP, resulting in an immediate shut down, like a desktop computer would do (not even in sleep mode, as laptops do when battery is low).

Coming hours I'll do some more tests and will dive into the error/system logs.