I'm an intern who recently joined a product based company. Recently after completing 2 tasks successfully, I've been promised a full-time role and right from that time my manager has assigned me to develop a new feature which requires in-depth knowledge about the product codebase and being a fresher I really feel incompetent to complete it within the stipulated deadline. I've not been given any induction/training regarding the product codebase.
Whenever I approach my mentor, who had been assigned to collaborate with me, says that he can't teach me everything and I have to figure out my solutions to my problems on my own. I really tried to cope-up and asked other team members working on other things to provide me KT(Knowledge Transfer) but they said they are busy and I should talk to my manager.
I'm still an intern just offered a full-time opportunity and I'm really not sure how telling my manager that I can't complete my assigned task within time would turn out and what impression that would create. But even my mentor once said that I have been assigned an unrealistic project that's impossible to complete with the knowledge of a fresher.
What should I do in this situation? I've been attending the office daily, sitting throughout the day, understanding literally nothing and then at the end of the day asking silly questions to my mentor.