Chosen Solution
I replaced my battery and trackpad, and everything was fine (computer booted, charged up the new battery etc.). Then, I noticed that the trackpad was too hard to click, so followed instructions to make it better (turning the star-shaped screw). Upon closing the case after this, and trying to boot, the computer started to do so normally, then within a second or two, stopped and went dead. Now, no MagSafe green light, no boot at all. After reading some posts, I disconnected the MagSafe and the new battery, and was going to wait 24 h before trying again. Also tried plugging in the MagSafe (60W) briefly after all as unplugged for ~15 min, to see if green light came on – it didn’t. So, have I blown something inside? Should I just be patient and try again tomorrow? I am worried I shorted something…Used the IFixit Kit for all, but when screwing in the two screws for the battery may have touched something with the screwdriver…Used the plastic thingy to get the battery disconnected, so that should have been ok… Any advice? Thanks!
Sounds like something on the logic board has shorted, if it turned off after a couple of seconds. Check the charger IC area, it is about the 4th large component up from the battery connector, and the chip has a little 625 written on it. Check for anything burnt, and make sure the pins around the chip look shiny, and not dull or burnt. Damage to this area can cause the dim green light issue, and is common. Let us know how this goes.
OK: here are the pictures:
