Foolproof power supply interfaces

I'm not sure it would help. What do we get when we try to make things foolproof? A friend asked me to fix his mains powered radio which he said used to work but had stopped working. I thought the mains lead looked rather flimsey but I said I would take a look at it anyway. I opened it up and found that the power went directly onto the PCB where there were some damaged tracks. There was no sign of a transformer or other evidence of a power supply section. I asked my friend if anybody else had done anything to the radio before he asked me to look at it. He said there used to be a big black heavy lump of a moulded plug on the end of the mains lead but he got someone to cut it off and change it for a normal sized plug because it wouldn't fit into the socket he wanted to use it with which was too close to his worktop. He didn't recall hearing a bang when he first plugged in the new arrangement. Regards, Peter Coghlan.