New PC build that worked after install of windows, now won't boot

[Jasper2402]

Hi guys, I'm new to the forum and sort of new to PC building. Last week I build a pc for my friend. It has a Ryzen 1600AF CPU, ASUS TUF gaming pro b-450m motherbord, Crucial RAM CT8G4DFRA32A 8GB DDR4 3200 MHz CL22 and a Radeon RX 570 GPU with a Samsung 980 M.2 NVME 500GB SSD. When I build it, it worked fine (but it only had 1 RAM slot, since I was still waiting for the other to arrive. I installed windows, and everything was still good. Then The other RAM came, plugged it in. The PC turned on but way slower then first, and after updating windows and restarting. It didn't boot at all. The power is on, the cpu fan is spinning. And the RGB fans connected with a sata cable are working fine. And after a couple minuts I get a black screen with a white _ (the screen is fully black with 1 white underscore in it: _). Then after a couple more minutes, the motherbord logo apears, but I can't acces the BIOS. What do I do now? How can I fix anything if I can't acces the BIOS?

[Rahul Vivek]

Remove the new ram and then test the pc. Your motherboard has 4 ram slots so when you install it in make sure the 1st and the 3rd ram slots are occupied.

[Jasper2402]

I put the RAM in the prefered RAM slots as indicated by the motherbord, in this case 2a and 2b. I removed the 2nd one I put in, but its still the same.