[SOLVED] Black Screen after installing new RAM - cant go back to old RAM either

[Jorvalt]

System specs
MOBO: Msi B450 Tomahawk Max
CPU: AMD Ryzen 5 3600
GPU: Nvidia GeForce RTX 3080
PSU: Corsair RM750X
RAM I was trying to install: Corsair Vengeance RGB Pro SL 16gb (x4)
Old RAM: Gskill Aegis 8gb (x2)

So here's the problem. I try to install this new ram by simply shutting off and unplugging my computer, swapping old RAM out, new RAM in, and... the computer seems to boot, but I'm getting no video signal whatsoever. The "boot" light on the mobo is also solid red, if that helps.
Since it wasn't working, I tried two at a time instead of all 4. That didn't work. So then I tried 1 at a time, 1 slot at a time. Didn't work. So then I tried to see if I could slot the old RAM back in and figure out if I could try booting in safe mode or something. Didn't work. Tried one at a time, didn't work. At this point I can't even get this stupid thing to boot properly, with the OLD configuration it already had, let alone boot it with the new and expensive RAM I just bought.
I'm out of ideas at this point. Please help.

 

[Deleted member 362816]

Clear the cmos. Unplug the pc from power and pull the button cmos battery and let it sit for 5 minutes. Or lookup the location of the Cmos jumper in your manual and do that.

 

[Jorvalt]

So uh, update. I was previously trying to work on this on my desk, standing up. I decided I was fed up and took the whole thing off onto the floor. Checked all the cables, re-seated the GPU (because why not and also because there was a SATA cable plugged in underneath it that I wanted to make sure was still plugged in (it was)) and put all 4 sticks of the new RAM in. Then just plugged the computer back in with minimal peripherals (1 monitor + keyboard) and it worked. Black screen with text saying there's a new CPU or memory installed and asked me to do setup, so I did. Now it works fine.
I'm not sure what step of this actually did something, and I sincerely apologize to anyone in the future who may come across this post. Solved, though.

Clear the cmos. Unplug the pc from power and pull the button cmos battery and let it sit for 5 minutes. Or lookup the location of the Cmos jumper in your manual and do that.

In all honestly, this probably could have helped. Maybe the problem was I didn't wait long enough between swapping RAM? In either case, if this problem happens again when I try to put in new RAM sometime in the future, I will definitely try this.