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Hi all, i’ve bought a MacBook Pro Early 2011 A1278 model 2nd hand. Changed some faulty plastic keys, Changed in SSD Kingston, Put 2x4gb Crucial 1333mhz. All was good and perfect. Only the battery has got more 1300 cycles, so I decided to buy a new one. After replacing the battery it started to give me some problems… It descharged and never restarted working correctly. I have tried also to put back original battery without any chanche. Now it give me a green led on the power charger, but no switching on. Actually I can switch only with this:

  1. remove the power charger
  2. press power button for 2-3seconds
  3. connect the power charger
  4. leave power button
  5. it starts with full fans load, not sowing battery status, no led on power charger, and if I disconnect the power it shuts down. I have tried to put back original HDD, original RAM, original battery… no changes. I have last SMC version: 1.68f99 It’s a MacBook Pro early 2011 with i5 2.3GHz. I Appreciate your help. Update (04/27/2020) Dan, thanks for your answer. Yes, i always follow ifixit procedures… i’m lovin it! however here my pics

It sounds like you damaged the logic board somehow. Did you follow the this guide to the letter? MacBook Pro 13" Unibody Early 2011 Battery Replacement Lets do some inspections here remove the bottom cover and take a few sharp detailed pictures of the logic board so we can see things. Post them here Adding images to an existing question