Swift advice for our swifts please?!

Last year we had a lovely family of swifts nesting in our roof. They are very welcome to return and I have read that they very well may do so this year. However, daddy swift has slight navigational issues and three times last year ended up missing the entrance to his nest and plopping down the wall into the space behind our bath panel- my partner opened it up and left the windows open each time and he seemed to have worked it out. BUT we have had some work done and now the drop from roof to bath has become blocked. I’m worried that daddy swift will plop down there again and get stuck and die as we can’t rescue him now :-(

Should I put a ladder up and block the old nest off and put a swift box up there for them? Or is it too late and I would do more damage than good? What’s the best thing to do as I know they might arrive very soon!!! Thank you in advance!