Will buy-side internships help to get into sell-side? or backfire?

always want to do IBD, but things did not go well with applications,,,I know more commonly sellside experience will be helpful if you wanna go to buyside,,,,,my situation is,, I had one internship in UK based mutual fund, recently been offered an non-paid internship at a boutique PE firm(still don't know whether to accept or not),

1, will PE internship help during resume-screening for IBD? what do you think a 3-month committment without getting paid? worth it? Am I going to be better off looking for some more IBD-related internship rather than taking internship in buyside?

2, correct me if I am wrong, does IBD just simply disfavor guys with buyside exposure?? I had many friends interned in mutual fund and got problem getting a interview

any feedback is appreciated

thanks!