I decided to clean out my CPU fan as it was clogged, when I assembled everything again it won't turn on 🙁

It's an old desktop PC. There are no lights glowing on the motherboard at all, though there is none specifically labelled "power". Just CPU, RAM, BOOT. None of these light up, not even a flash when it starts.

I have reseated the RAM, CPU, power cables. Removed the GPU to check.

The cord leading in to the PSU works but I don't have a way to test the PSU itself or the out cables, but I have reseated them at each end.

This PC was working fine before. But with no lights on the motherboard I suspect either the mobo or PSU?

Mobo is asrock x570 PSU is silverstone 650w strider gold S series

Any help appreciated!

Edit: I made a new post asking for hardware recommendations.

Edit 2: I managed to get a light on the motherboard, going to buy some more thermal paste and keep tinkering to see if I can get it started!

Edit 3: I never got that light to go again. In the end the comments on the other post convinced me that I had all that I needed for what I wanted (no upgrade needed), so I changed tack to seeing how to fix it. I had suspicions about the power connection still, so I bought a cheap PSU and tested it, no change. Then I bought a new motherboard (also a pretty cheap one, the cheapest that had what I needed and was also in a local store) and in the end that was the issue. Everything is up and running again now! Thanks for all the help everyone, you can now settle your bets.