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I have replaced the battery in my MacBook Pro model A1398 following your guide. Now when the MacBook restarts, the fan is running very quickly and the MacBook is running VERY SLOWLY as if the CPU is being throttled to a point where the system is unusable. I have tried following steps to reset the SMC but this makes no difference. Please help!
Try starting up in Safe Mode by holding down the Shift Key on start up, let’s see if this slow down is related to software. I have seen this several times, especially if you are running an older version of MicroSoft Office.
