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Hi, Wondering if I might have a bad logic board, or maybe (if lucky) a bad magsafe board, or something else. Curious to get your take on these details. Background: battery was replaced about 9 months ago, but this computer (a backup these days) wasn’t used the vast majority of the time since. Haven’t had any trouble previously with this machine in 10+ years of ownership aside from battery replacement, until now. There is no physical indication the newish battery is bad e.g. bulging, although the previous one was and temporarily deformed the trackpad (but didn’t break it). Symptoms when not plugged into the AC adapter: Battery LED indicator lights don’t flash anything at all. Computer won’t power on. No lights of any kind anywhere. Tried holding SMC, PRAM hard reset keys, but obviously since it’s not even powering on, it doesn’t do anything. Symptoms when plugged into AC adapter: Computer won’t power on normally.Tried PRAM, SMC, etc. hardware resets again, also doesn’t do anything.Magsafe adapter comes on the regular bright green (doesn’t show orange).Voltage on the visible part of the MagSafe board reads 16.6V between ground and supply, and around 3V between ground and “sense” IIRC.Battery indicator lights initially flash one dot several times (if I press within a few seconds of connecting the adapter). After this initial period, all battery LEDs blink green five times.If I take the back off and disconnect the battery from the logic board w/ AC still plugged in, the battery indicator LEDs also blink green five times.Finally, there is a faint and very high pitched noise coming from either the Magsafe board itself or somewhere near it on the logic board. If I press the power key on the keyboard, the frequency changes slightly. Not sure if this is capacitor whine or inductor coil whine? Then I found this dude’s YouTube video: https://www.youtube.com/watch?v=Inoj8Pwy… Remove the adapter. Hold power button 5-10 seconds, then plug the adapter in while continuing to hold power button. After a few more seconds, voila, the fans start whirring up (blasting of course, despite clean fans/radiator fins).Get the boot tone with the boot screen!Then about 40% into boot progress bar, the computer shuts down and restarts, in an endless loop of rebooting.I have tried the recovery screen using internet recovery and ethernet cable, but it just restarts eventually. Also tried SMC and PRAM resets here again. No success in breaking the cycle.Although I’ve never managed to spill liquid on the MBP, I read up that shorts in the keyboard/keyboard connector could potentially be causing a similar endless rebooting cycle. So I manually unplug the keyboard flex connector from the logic board in between cycles. But it keeps restarting after 40%.At all times during this cycle of rebooting, the battery indicator LEDs will not flash anything when the button is pressed. That’s the extent of tinkering I’ve done thus far. Any things this rules in or out? Many thanks in advance!
If the battery checker LED’s are not lighting up then the battery is likely dead. If the MagSafe LED is not lighting then the MagSafe charger and/or the DC-In Board connector are dirty or damaged. I would review this Apple T/N Apple Portables: Troubleshooting MagSafe adapters Here’s an example of a damaged MagSafe port
You may need a new charger Apple 85W MagSafe Power Adapter (for 15- and 17-inch MacBook Pro) make sure you get a REAL unit directly from Apple. Many knockoffs are being sold claiming as being real Apple units or so called OEM which they aren’t! Don’t Replace Your MacBook Charger With a Cheap KnockoffOEM MagSafe Chargers vs Cheap Imposters: Teardown for TruthLacking safety features, cheap MacBook chargers create big sparksFAKE Magsafe MacBook Chargers on eBay - Watch before buying a Mac Charger
