Ram slot issue

[bosin]

I built a new PC earlier this year (2021) and when I tried installing my ram in the A2 B2 dual channel slots the PC won't post and has a DRAM post code light. I did a little bit of troubleshooting on my own but I am at a loss on what to do next. The CPU was installed correctly and was not dropped into the socket so I don't think that there are any bent pins but I did buy an open box MOBO and didn't inspect the socket prior to CPU installation. In regards to the RAM I tried switching them around and tried different slots. I tried A1 B1 config and same post code. I tried single channel option with just individual stick in the A1 and B1 slots and still having the DRAM post code. I even tried turning XMP on and off with the same DRAM fault code error results from the A! and A2 slots. A1 and A2 is stuck on the DRAM error code. Both the B1 and B2 boot completely and register on CPU-Z but registers as 16gb in single channel.  I would think that if a slot was dead it wouldn't register if a ram stick was installed in it and would go on to the next ram slot. I am a newbie and I'm still learning. I have successfully built 3 computers by watching Linus Tech Tips on YouTube. "LTT store dot com" lol. The specs of the problem build are: ASUS TUF GAMING Z590-PLUS MOBO, 16GB (2x8G sticks) Corsair Vengeance LPX 3000MHz CMK16GX4M2B3000C15, 3 M.2 SSD at a total of 2.25TB of storage, GPU AMD Radeon RX580 GTS BLACK EDITION 8GB, Cooler Master MasterLiquid ML240L, case Cooler Master Masterbox TD500 Mesh, PSU EVGA 750 BQ semi modular and the updated latest version of Windows 10. I'm just wondering what the next step for me is. Like I said, I'm still learning and I would like to continue to learn. I've watched an insane amount of LTT YouTube videos and I have learned to trust Linus and his crew's tech chops. I would like Linus to respond but I'll accept help from any other tech savvy person.