PC won't post after new GPU

Here's what happened:

I bought an RTX 5070 from Walmart.
Came home, uninstalled my drivers with DDU ( I had AMD before), restarted my pc. Unplugged it, put the new GPU in, turned it on, RED CPU LIGHT turns on the MOBO and it does not post.

Specs:

• MOBO - B650 A ELITE AX V2
• CPU - Ryzen 7 7800x3d
• PSU - bequiet! pure power 1000W (Model L12-M-1000W)
• RAM - Teamgroup 32 GB DDR5 6000 (2x16gb)
• OLD GPU - Gigabyte RX6650xt
• NEW GPU - PNY RTX 5070

Here's what I have tried so far:

• Tried booting without GPU
• Tried booting with old GPU
• Tried to boot with one ram stick on Slot 2
• Switched the ram stick and put it on Slot 2
• Tried to boot without any NVME's or HDD connected to MOBO
• Reset CMOS
• Reseated CPU.
• Tried booting with different PSU
• RMA'd the CPU. Got new CPU. Tried booting and nothing. CPU light still comes on.

I RMA'd my motherboard, because I thought that was the only thing possible but Gigabyte are sending me the same motherboard, stating that the technician posted with no problems and their further testing did not warrant any problems with the motherboard.

So, at this point, I don't know what the heck is wrong with my computer. Please send help!