First time for this, opinions please.

Greetings,
I have been buying and selling on A'Gon fo almost 4 years, over 160 transactions. Not a hitch until a local transaction yesterday. I sold a CD player (Rega Jupiter) to a member who lives in my city, so no shipping involved. He came over to my house, listened to player, liked it, bought it and took it home. Later that afternoon he called and said CD player would not power up. Strange as it worked for him for awhile until he changed powercords. After some discussion of checking this or that, it was determined that powercord was changed while on/off switch was still on. At this point I said there's the problem, switching powercords with power still on likely blew a fuse or some other trip device. He did not totally agree, but said it must be an explanation. At this point I must add, said member does not hold me responsible in any way. He was just seeking my advice as to whether I have ever had any trouble of this sort.
My question is twofold:
1. Do you think changing powercords while player is powered up could cause this (I do).
2. Do you think I have any obligation to help at this point? Once again, buyer is not holding me responsible, but I have been worried about this all night. I really feel bad , as this is not a small purchase for him.
Thanks in advance,
Dan