S21 ultra battery bulging

[zook5972]

I have recently replaced the screen on my second-hand Ultra.I hadn't  resealed back yet.It was working fine then suddenly my SIM card wasn't reading.When I checked connections I fund the plug loose.There is a fairly sharply defined area (it almost looks deliberate) on the bottom right corner of battery  that is raised making cables tight and can be felt through the case.I don't use phone enough to tell if it is affecting performance. Fortunately with back off I was able to reconnect cables and seat battery somewhat better and replacement would be easy.Any similar issues or replacement battery suggestions? 

[AndrewL]

@zook5972: As the Galaxy S21 is a sealed unit, batteries should only be replaced by an engineer at an authorised Samsung service location. If you have performed some repairs yourself, or arranged a repair at a third party store, then this can result in unforeseen issues such as the ones you are experiencing at the moment. If your battery is swelling then this is certainly a concern, therefore I recommend reaching out to the relevant support team in your region to arrange for the device to be inspected. Please be aware, however, that if unauthorised repairs are identified during the inspection, then this would result in your warranty being voided. 

[antikythera]

It's 2nd hand so there is no warranty. However, is the battery itself bulging or just badly fitted? If the battery is bulging do not use the phone until you can get a new battery because it is not safe in that state