Pc Repair

So what happend is I was streaming a tv show on my PC from the internet when out the blue it shows me a message saying my PC ran into some problems and has to restart so I decided to leave it to restart

Then it just switched off and wouldn't restart so I then tried to start it up manually but nothing. My PC switches on it seem light's flash, DVD drive opens and closes but nothing on my screen my monitor shows no signal. And the light that indicates my harddrive is in use is dead it's almost asof my hard-drives aren't connected.

I've disconnected everything and put everything back together with no luck and there is no beeping to indicate what the problem it. I'm still quite new to repairing a PC and I would like to know how I could fix this specific issue.

I bought the motherboard and HDD from a Friend and it worked perfectly I installed new HDDs to up my storage and I've removed them with the same end result it won't boot up

Please can anyone help