If the light flickers when you move your head, the issue is almost certainly a fatigue break in the power cable where it enters the lamp housing or battery pack. Step-by-Step Cable Repair
This guide will focus on the most common repair: petzl myo xp repair
Some advanced users ask about swapping the old Luxeon LED for a modern Cree XP-L or Nichia 319. The Myo XP’s driver does not output enough voltage or current for a modern 3V LED. Direct swapping will result in a dim light or immediate burnout. Stick to stock, or buy a modern Petzl Actik. If the light flickers when you move your