You'r ID covers 7 different devices… but generally 3 successive tones, a 5 second pause (repeating): This indicates RAM does not pass a data integrity check.
That means the RAM is lose, the RAM connetor is damaged, or the RAM chips are damaged.
So go over the RAM slots (there's two you know) again. Check that the RAM Chip is completely pushed in as far as it will go and the "wings" (aka locks) are in position. The link is generic yours should be similar
You do not need to completely reassemble the machine to check the RAM but.
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