Sound like it unfortunately was not the circuit board at the front of the PC that does power/reset/usb/hdd activity stuff. It sounds like the PSU probably does work on the basis that it powers fans up during your test. Whilst it could still have a fault, let's assume it does work for now. The next step really is to try to eliminate what else could have broken. You can either work backwards by starting to take more and more stuff OUT of the case (i.e. Disconnect components) or you can work up from the bare minimum. Easiest for you would be backwards since you are new to this kind of thing. So on the basis you could do the below:
1: Take the graphics card out. Check youtube for how to do it but there will be a little tab again that you have to flick to get it to come out of the slot. You will also have to undo a screw holding it in near backplate. Once removed, you can plug whatever lead you had going to your monitor, directly into the actual motherboard VGA/DVI/HDMI ports which your motherboard does seem to have. This would eliminate the graphics card. You can still leave all of the cables unplugged that connect from the front switch/usb port area to the motherboard. Then again, use the screw driver to bridge the connections to attempt to start it.
2: As above but unplug/remove any drives like nvme drive, sata drives
3: As above but unplug all fans except the one above the CPU that is black and says AMD on it.
4: Try booting with just one single RAM module in the motherboard. Sometimes this requires a specific slot for it to work so you can try both.
Remember the PSU needs to be on in case you have pressed the switch on it to off during your testing.
If after all of the above you still see no life or lights or action, the next thing would be to remove the entire motherboard from the case in case there is water underneath it or a screw/bolt on the case is creating a short against the board or something like that.
If after that it still doesn't work, it's most likely the actual motherboard got broken.
1: Take the graphics card out. Check youtube for how to do it but there will be a little tab again that you have to flick to get it to come out of the slot. You will also have to undo a screw holding it in near backplate. Once removed, you can plug whatever lead you had going to your monitor, directly into the actual motherboard VGA/DVI/HDMI ports which your motherboard does seem to have. This would eliminate the graphics card. You can still leave all of the cables unplugged that connect from the front switch/usb port area to the motherboard. Then again, use the screw driver to bridge the connections to attempt to start it.
2: As above but unplug/remove any drives like nvme drive, sata drives
3: As above but unplug all fans except the one above the CPU that is black and says AMD on it.
4: Try booting with just one single RAM module in the motherboard. Sometimes this requires a specific slot for it to work so you can try both.
Remember the PSU needs to be on in case you have pressed the switch on it to off during your testing.
If after all of the above you still see no life or lights or action, the next thing would be to remove the entire motherboard from the case in case there is water underneath it or a screw/bolt on the case is creating a short against the board or something like that.
If after that it still doesn't work, it's most likely the actual motherboard got broken.
New one should be arriving Tuesday