why is my phone volume buttons not working properly

when my phone is on silent mode my volum completely turns off. no sounds on music apps or anything and i can not turn it up. when i try to use my volume button when my phone isn’t on silent mode it only works sometimes. the volume usually only controls the ringer volume and soemtiems the volume down button turns my volume up vice versa. it also doesn’t let me turn off my phone when my phone is on silent. i have an iphone 11 that was recently fixed for water damage and a screen replacement. i have reset settings and tried adjusting many setting and nothing seems to fix my issue.