After changing the processor, the first and second RAM slots do not work, how to fix it?

Question

Processors

Hello everyone, this question:
Mother: ASROCK Z370 PRO4 decided to change the CPU from i5-9400f to i7-8700k.
After replacing 1 and 2, the RAM slots do not work (next to the CPU), all coolers work, the screen is black, everything is fine with 3 and 4.
RAM (KIT Corsair LPX 2400, work fine)
Rolled back BIOS was version 4.30 to 3.30 then 3.10 (no results)
Dismantled everything again, looked at the socket, there are no bent legs, burnt ones too.
Everything is smooth and clean, who faced what the problem could be, give advice!
I can send a photo of the socket if needed.

Answer 1

1. There may be dust in the slots.
2. If not dust, then to the service.

Answer 2

open the socket and look for bent legs