Red blinking LED and system not booting [B550 Gaming Gen3]

[isea159002e5]

Hello! I've recently been messing with my SSDs (I have 2 SATA SSDs in the system) to work on another project of mine, but, after putting them back together today I attemped to start the computer and found out it hangs with a black screen and the CPU light on in the debug LEDs.
I should also note that the fans do spin up during this time, including the GPU fan, and that I've used this system before in the exact same configuration.
I doubt it's an issue with the cpu as I bought it new just a couple of months ago. I got it to reach the "BOOT" state once, never have been successful in doing so again.
In my attempts at making it work I also attempted to flash the BIOS with the relative button. I tried with 2 different USBs (a 2 gb one and a 32 gb one, both formatted to fat32), but got a red light that blinked 3 times before stopping.
I also tried resetting the CMOS by shorting the 2 pins (JBAT1 i think) for 15 seconds and by taking out the battery, neither worked.
My specs:
- Ryzen 7 5700X
- Nvidia Quadro M5000 / M4000 used for testing as well
- Corsair CX550
- 32 gigs of G.Skill Ripjaws V RAM
- B550 Gaming gen3 mobo

Ask me anything to help you help me.

 

[FlyingScot]

A believe we have seen instances of a red CPU LED being caused by a bad SATA cable, connection or internal short within the SSD. I would try disconnecting storage drives and USB cables, too. If you have a multimedia storage device, that could be another source of issue. A USB-C cable inserted the wrong way round in the header can definitely lead to red CPU LEDs. So try that line of logic.

In regards to trying to get a flash drive to work with the Flashback button, I think this guy is on to something.

Please let us know if your find your issue. We all learn together.