Hi guys! I would need your help. I just recently got a used MGP 9001 tube Marshall preamp. I've put in the screw that was too long that touched the base of the ON/OFF switch on the PCB plate that is connected to the mains cable. I clicked the ON button to turn on the preamp and I saw lights in the house go out and a short moment of electricity burst behind the switch (obviously where now the burnt area is). Although I could swear I heard the fuse go off, it does not look damaged to me. I have no replacement fuse for this one. It says T100ma (I am using preamp at 240 V, Europe). Then I've removed the screw and went on to turn the preamp ON again, nothing happens, and no LED lights turn on. The thing is definitely not ON. Did I blow the switch? Or the whole thing (unit)? Or should I try getting this fuse and then try to turn it on? Looking at the board nothing else seems bad or burnt and there are no odd smells. I was really looking forward to this preamp but I messed it up. I really appreciate your tech input on this problem. Pic of the culprit area and the damn screw is attached. Thank you so much!