Can't boot a PC

[IvanMuse007]

So I have a Gigabyte GA-H55M-S2V(old) that turns on for 1 second and shuts off and it does that repeatedly
It's not the PSU
I don't think it's CPU because I tried to power the mobo without it and it did the exact same thing
RAM isn't the issue here neither because it works in another system with same parts
I tried clearing CMOS with jumper
And fans would spin only when I wasn't touching the jumper
Here's a video of it
https://youtu.be/SQxbpL5ut24
Anyone have any other ideas I could try?

 

[captaincharisma]

make sure the CPU fan is connected and seated right because the CPU may be overheating

 

[IvanMuse007]

It was connected before
I removed it before when I tried to boot without CPU and I haven't put it back fully
I don't think that's the issue here