And then back that up with career advancement metrics designed to motivate individual cops to ensure their camera gear is working and reliable. Missing 2% of your bodycam footage a week without having made a documented effort to get it repaired/replaced is a warnable offence. Missing more than 5% you get your pay docked. Miss 5% more than twice in a calendar year is a sackable offence. Any claims made in court about events that happen while your bodycam footage is unavailable remove your usual police department protection, and expose you to civil suits that you're normally shielded from. If a civil suit rules that "in the balance of probabilities" you were wrong, you become personally exposed to damages.
As the law & order types love to say "If you're not doing anything wrong, you've got nothing to fear." It cuts both ways.