Gakex is down and TronTrade shows GEX as invalid market...? Are you exit scammed? I have some money frozen if you care

Try to attach the new PSU and short the mobo pins, if you dont have power buttons on the mobo (?) Maybe you dont have restore on power feature.

Do you have PC? Remove the GPUs and put them 1 by 1 in your regular PC to check if they are dead...? You can do this with ram as well.