iPhone X problems

My iPhone X randomly shuts downs and then turns back on. The volume buttons are not working - both the physical one, the slider one and the one in settings. It says it is stuck on full volume but there is no sound, however when I plug it into ear phones or a speaker everything works again. I have try a hard reset, it temporarily fixes the sound however reverts back to this eventually. Sometimes after a hard reset I will get sound for 5 minutes or a week - completely random. I have also updated the phone to the latest IOS. This iPhone is also out of warranty so I cannot get apple support. Does anyone know how to fix this?