You could have bad RAM or a bad logic board. Read Power On Self-Test Beep Definition. Considering that it is a portable and RAM can come loose more easily than in a desktop, remove each RAM module and re-seat it. This may not solve the problem but it's worth a try and it's certainly cheap to do.
Jon
macOS 11.7.10, iMac Retina 5K 27-inch, late 2014, 3.5 GHz Intel Core i5, 1 TB fusion drive, 16 GB RAM, Epson SureColor P600, Photoshop CC, Lightroom CC, MS Office 365
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