If the switch is failing, it can be difficult to replace due to the specific height of the original micro-switch. Some users suggest cleaning the dome spring of the switch as a simpler fix. Critical Safety Note HELP! Petzl Myo XP malfunction - UKC Forums - UKClimbing
The Myo XP headband attaches via two plastic clips. In 2021, the original Petzl band is no longer sold. Here is the workaround: petzl myo xp repair 2021
Petzl explicitly states that modifying their equipment voids certifications and may compromise safety. Repairs should only be undertaken by competent individuals. Defective safety equipment should be retired. Short story — "Petzl Myo XP Repair 2021"
The rubberized buttons can wear out or lose contact with the SMD switch underneath. Open the front lamp housing (4 tiny screws)
I can provide more detailed soldering tips or help you troubleshoot the switch specifically.
Electronic waste is a growing concern. Repairing a headlamp extends its lifecycle significantly, preventing the lead, plastics, and electronics from entering the waste stream.