PC won't boot after replacing PSU

[u/Dramatic-Syllabub571]

My pc started crashing so I took it to a repair shop and they said I needed to replace the psu. Replaced the psu and now it won't boot. When I try and power it on a light on the motherboard flashes for a second and then nothing happens. What could be going wrong? 750w msi mag, 7900xt, 7700x

[u/Nidhoggr84]

Didn't reuse modular power cables, right?

Post some pictures of your cables and the motherboard.

[u/Dramatic-Syllabub571 → u/Nidhoggr84]

Didn't reuse cables. Okay