MacBook Pro - Don't Boot After Flat Battery

How long do you let it charge before you try turning it on, and what wattage power supply are you using? The system should boot just fine sans battery with a proper power supply. I recently ran into an issue of a completely dead 2009 MBP battery (luckily removable), but it boots just fine provided an 85W power supply is attached (no go with 60W--no power indication at all).

Unfortunately I have to concur. The battery itself has a chipset (well, in the past 5+ish years) that we've seen the need to reset every so often. Our hardware tech had never been able to get any good info out of Apple on it, but I'm glad that you found a fix. We've seen this for ~5 years.

Usually when I find a laptop with a completely drained battery, I have to plug it in to power for at least 5 minutes before the computer will turn on again. Sometimes the battery indicator LEDs won't even light up until after this time. Even though the computer is plugged in, a dead battery can still impede the ability for it to turn on until it has at least SOME charge to it.

Try an SMC reset as well.

@betty02 - All I can offer you is some solidarity. I run through the same battery disconnection process as you - it appears to be the only effective remedy.

FWIW I have advised our users not to keep their chargers connected once the issue occurs. The computers end up getting extremely warm while stuck at the "I almost want to boot" stage, likely because the fan is not running.

Unfortunately, you won't get any definitive reason unless you're certain about the last known state of the system. Like @mattware mentioned, if disconnecting the battery, an SMC reset will likely have resolve it without having to resort to removing the bottom case.

some possibilities may include
- incomplete sleep
- sleep image didn't finish writing before power loss

also make sure when powering it back on, make sure it's connected to a MagSafe with the sufficient wattage, a 45W MagSafe from a MacBook Air will not chime on a MacBook Pro that needs a 85W MagSafe with a battery at near 0%, at least not without letting it slowly charge up to supplement the insufficient power from the MagSafe, which is what @tkessler experienced.

Cheers chaps glad to know I'm not the only one! SMC reset never works. Always found unplugging etc is the only solution so guess it's just one of them things I will have to keep doing.

All sufficient charges and had some we've left for 5 minutes or 5 days on charge and the issue has been the same. So will keep working!

Good to know I'm not the only one though, always makes it a little bit easier!

Also having this issue. After we pushed out an update to 10.11.2, people weren't restarting their machines and letting them run down over the holidays. Had to remove the battery quite a bit lately to get them to boot.

A MacBook Pro (Mid-2012) came across my desk, exhibiting the symptoms, and after a round of component isolation, I started to look at the SMC and EFI Versions, because the OS X version on the system wasn't current, and firmware updates are currently being updated and delivered through OS X updates.

It turns out an SMC Firmware Update addressed this in 2013
https://support.apple.com/kb/DL1633?locale=en_US