I have an offer from Siemens for Robotics Internship, it seems that due to some unforeseen reasons, I have to graduate before starting the internship, I would still like to do internship on OPT. Is it possible? Or they only hire students who are in school when they are doing the internship.
Part time internships while studying are the norm. It could be possible that they want only full time internships instead, which could be the reason that they want you to graduate first. Just ask the recruiter at HR for their motivation.