Just another guide for you, I’ve just done this {28 JUNE 2019} solutions for 3 Beeps 1. Upgraded your RAM 2. RAM undetected If any of your RAM goes undetected, also the chime doesnt happen and the only sound is of 3 concorrunt beeps then: 1. Press and hold the power button so the fan goes off. 2. Loosen the 4 screws mounting the RAM holder slot a bit. 3. insert small folded paper or old credit card cutting as plastic swag/cuff 4. Power your Mac. [If this works, Hurray!! Close off the lid and get back to work] If this doesn’t. 5. Tight the 4 screws, arm your Mac. This should make it work, i suppose. 6. If it does work, thank me @bakedsamosa and iFixit for simplifying the replacement. 7. Close the Lid already. Getting back into service Steve Job’s best creation.