I have an aging fleet of Macbook Pros (mid 2012) that have developed a problem since upgrading to 10.11 El Capitan. The computer will try to boot and power on, but never get to the gray screen, it stays at the black screen. The fan runs, the computer gets hot if left trying to start, but it never boots and holding down the power button is needed to get it to stop. The only way to get it to boot is to take the bottom case off, unplug the battery, drain the logic board capacitors with the power button and then plug the battery back in. It will then boot right up.
I'm virtually sure it is not a hardware problem since it never occured prior to 10.11. My gut tells me that it is somehow related to letting the battery die with El Cap, but I'm not sure about that. I've seen it about 30 times in the last 3 months since upgrading to El Capitan, and am now starting to see it happen a second time on computers it has happened on before.
Anyone have any helpful suggestions?
