Why a battery fault so often looks like a broken remote
Falling cell voltage does not produce a clean failure. It produces a remote that works from the sofa but not the doorway, then works only when aimed precisely, then works only when you press hard. Every one of those stages gets reported as a hardware fault, and every one is fixed by two new cells.
The pattern is worth recognising because it saves you from the more drastic fixes. If the symptom is gradual degradation rather than sudden death, batteries are the overwhelming favourite — well ahead of pairing, firmware or anything wrong with the television.