The night time stuff can take years and to lessen the stress, don't punish him. He has zero control at night, so get him the bigger kids version of pullups or wake him before you go to bed to get up and pee until his body gets he needs to wake.
As far as during the day. I would first talk to your Pediatrician and make sure it isn't anything going on with his bladder or kidneys. He may very well not be able to help it. Once you have ruled out all the medical things not being an issue then do this"
Start going backwards. Put him in a pullups during the day, be matter of fact and take away most of his "big boy" stuff. Fold up his underwear and just say "I guess you aren't ready for this just yet".
Don't punish him, don't get angry, just say "well we have tried and if you are not interested in going to the bathroom like a big boy, all big boy priviledges are done with until you can show me you are ready". Almost like re-potty training. Any big boy toys or special priviledges he got for being 5 need to cease. He is a big brother so that will maybe push him a little harder to try and step it up. He has to go to bed earlier, no 5 year old TV shows and so forth. Not to be mean but to maybe get through to him that if he wants these things he needs to earn them back. Then it is his choice not yours and he has the control so it will be easier in the long run.
Don't shame him or make a big deal out of it, but explaining that he has to take time out to go pee. When he is at home, set a timer for every hour, tell him to please go try and make sure he does at least go try. It is kind of backwards but he hasn't been fully potty trained if he is still peeing his pants at least once a week. Getting the brain to connect to the bladder and teaching him again and over again to reconnect and associate he has to stop what he is doing and go so he doesn't pee his pants and hold it until he gets to the bathroom is crucial.
First rule out anything medical. Then if it is all good just go backwards. Most 5 year olds aren't going to tolerate anything associated with not being a big boy, so if you are whatever about it, then he may start getting the connection.
Good luck.