@seanhinze that sounds like a bad power button/volume flex. Since iFixit does not yet have a specific guide for that, use the one [https://www.nadiemellamagallina.com/en/manuales/smartphones-1/samsung-4/samsung-galaxy-a51-1200/pulsadores-y-teclas-laterales-10659|from here] It was written in spanish so you may need to use a browser that does the translating for you, if needed. Replacement flex can be purchased at many online stores in all regions :-)
While you work on your phone, take lots of pictures. Once you are done with it, take those pictures and create a guide for iFixit. That will help the next person that has a device with the same issues as you do. It's easy and fun to create these guides. https://ifixit.com/Guide/new The iFixit community will appreciate this.
Repair is War on Entropy!