Work through these checks in order
Note whether drain happens during use, overnight, only on mobile data, after an update, or after installing an app.
Use the built-in battery screen to compare app activity and screen-on time over the last day.
High brightness, constant navigation, hotspot use, background syncing, video calls and gaming can legitimately consume substantial power.
Poor cellular signal and high temperature can increase energy use even when the device is not doing much visibly.
Older batteries store less energy. If runtime has steadily declined across months, battery wear may be part of the issue.
Before an erase, restore or repair decision
Confirm what data is backed up, what a reset or restore will remove, and whether you still need access to account credentials or authentication methods stored on the device.
When professional service makes sense
Hardware damage, repeated power failure, liquid exposure, battery swelling, damaged ports, broken displays and problems that persist after low-risk software checks can require qualified inspection.