That's the usual Schaffner-Paffner behavior.
Schaffner used some shitty (I guess paper/oil dielectric) capacitors that draw moisture from air which degrades the dielectric. If equipment isn't in use for longer times, they blow up soon after the instrument is plugged onto power again. I wouldn't be mad at the seller, they fixed it as fast as possible and send you a working instrument. Be happy it didn't blow up in your lab, the magic stench is horrific!