Chosen Solution
I have iMac 21.5g” Model Number: A1311(11,2) (EMC No: 2389) (Intel Core i3) with black screen after upgrading to SSD. How I can diagnose it and fix it.
Go over all your connectors and connections again. Often those that were “thought” or “believed” to be good were lose, not snapped in, ribbon cables not inserted fully and locked. If this answer is acceptable please remember to return and mark it.
