My mid 2010 13-inch MacBook Pro running El Capitan frequently shuts down abruptly. I'll put it to sleep, and not long after it wakes up the entire system will die. Whenever this happens, pressing the power button fails to power up the system. The only way to power the MBP back up after it dies like this is to either reset the NVRAM or hold the power button for 10 seconds until the sleep indicator light blinks (not sure what the latter method actually does, but it helps temporarily). Once I do either of these things, I can boot to the desktop and use the computer. When I put it to sleep, the cycle starts all over again. Perhaps worthy of note are two other problems, neither of which worry me terribly but could be connected to the main problem: Spotlight refuses to search, and the battery is in "Replace Soon" condition. I've tried repairing disk permissions, for both the entire hard disk and for Macintosh HD. Thoughts?