Had a friend that sent a Yaesu FT917 (?) into Yaesu repair because someone plugged a morse key into the power accessory jack on the back and blew the unit.
Long story short--Yaesu claimed the rig was totally unrepairable and sent it back. I opened the unit, replaced a blown trace on the circuit board, and the unit was back in service--and working OK.
Kinda strange that Yeasu missed something that obvious.
I have heard about this. It seems they love to use the line, "The damage is consistant with a lightning strike, and there is nothing we could do."
Saying that, I did one time plug my headphone plug into the CW jack and thought I blew it. Several hams told me that was not the case.