Preamp/interconnects cause amp problems?

My power amp, which sat, untouched for 3 years, always on and sounding great had a short in the power supply (cap gone bad?).

I sent it back to be fixed and and hours after getting back had the same issue. Manufacturer replaced boards and related pieces and is sending back but said they found nothing that they think would cause the issue.

so my concern is it’s something here causing it. Even though the manufacturer put the amp on the burn in rack for a week I’m worried it will have this issue again.

is it possible my preamp or interconnects could cause this? I have a loaner amp in place now for a few months and have had zero issues with it (same everything and save outlet)
but it’s a different (lesser) brand.