Any recommendations for PC repair in London?

[Doctor]

Hi all,

Something's exploded on my PC and I can't figure out what it is. Lights, pumps, fans all come on but boot LED always on and no video out. I've taken it to a local shop but they weren't much help, said it might be CPU, I replaced it, still doesn't boot. I also replaced the PSU, still the same. I can't really afford to buy a replacement for every part of the system so looking for someone in London who can actually diagnose this for me.

Anyone had good luck with a shop in London (North London especially)?

 

[Doctor]

What I meant by explode: The PC suddenly shut down while playing a game, loud pop, burning smells.Then won't boot afterwards.

PC is my own build, AIO cooler. Problems started suddenly, no warning signs that I could tell.

Really hoping it's not the whole system fried

 

[Doctor]

Update:
MOBO was for sure dead, I got a new one today and the PC rose from the dead. One stick of RAM also seems to be gone, tried reseating it but it's not recognized and lights are also dead on it.

Now I need more help. I have swapped in a new PSU, CPU, and MOBO and it works, but now I wonder if the PSU or CPU were even the problem. Do you think it's safe to try swapping the CPU back into the new motherboard to check if it runs? The CPU is a 13700KF so I would really rather not eat the cost if I can return the new one.