After a CPU upgrade, my PC won't boot

Hey there - I just upgraded from Ryzen 3 to Ryzen 7, and I'm using an MSI B450M PRO-M2 Micro ATX AM4 motherboard. According to PCPartPicker, it's all compatible.

After upgrading, my PC makes its usual start-up noises, the fans spin, and the motherboard and GPU LEDs light up, but the front panel LED isn't lighting up - which is my indicator that everything is actually on and running. Nothing's showing up on my monitor, and I can't boot into BIOS.

I tried clearing CMOS as recommended in other forums with no luck. I then tried replacing the new CPU with my old one to see if it would go back to booting up fine, but I must've messed something up with that old CPU while removing it, cause it's not locking back into the socket properly.

After that, I removed every cable on my motherboard and placed them all back where they belong - still nothing. Fans whir, motherboard and GPU light up, but the front panel is dark, and nothing boots up. I'm out of recommendations, and I've got an appointment at a repair shop scheduled, but I'm asking for any other suggestions just in case. Thanks a ton