Windows 11 PC problems, looking for help

For context, I built my PC about 2 years ago. Last Friday, I went to turn it on after work, no bueno. The motherboard light near my I/O flashes red, but no other lights come on, no fans spin. Just nothing.

I replace the power supply suspecting that was my issue, wrong. Take it to my local computer shop, they determine it was my CPU (specs coming soon, I promise). They replace the CPU, re-attach my AIO, and send me on my way.

Get it home last night, reassemble it all, posts, boots into windows everything is honky-dory. Shut it down last night just before watching late night television. Get home today, won’t turn on… AGAIN. Same red light near the I/O blinking. There’s no way another CPU died, right? Clearly this must be an issue with my motherboard?

Specs: ASUS ROG Strix Z790-F mobo
Intel i7 13700kf cpu (replaced yesterday with a 14700 kf)
Corsair DDR5 RAM
4070 GPU

Help me determine what the issue is.