DS was almost 3 when he was potty trained, it took him about a week or two. I honeslty think he would have strted earlier but I was at work full time and his dad was at home with him when I was gone, he just didn't care.

If you think it's the restroom then get a potty for him, get him familiar with it! Have him sit on it whenever he wants, where ever he wants, with or without clothes! Maybe he just needs to be eased into getting used to the potty itself. We also had a great book, it helped DS alot! This really is an adorable book, DS and I would giggle through a lot it and I think that helped ease him some.

(ours also made flushing noises, DS loved to push the button to "flush the potty")

ETA: I also had many older mothers of boys tell me that they potty trained in the summer, letting their boys spend a lot of the day outside in t's and undies, if they had an accident oh well. I know it's not for everyone, "going" outside and everything but you never know, it may be something you'd like to try.