AFAIK it happened to me twice when i owned zebronics 400watts and zeb 500 watts.But i still own 500watts as spare if my current zeb730watts blews up.
1) Is it possible that the psu suddenly got a short circuit connection inside it?
not everyone is lucky.yes its possibel
2) Am I going to get an RMA for this type of problem?
no doubt you should get it
dun worry bro be cool