beats flex won't turn on or light is off when charging

Appears that your Beats Flex are completely unresponsive, which usually points to either a drained or faulty battery, a bad charging cable, or a hardware issue.

First, make sure you’re using the original USB-C cable or a certified replacement. Some cheap cables don’t provide proper power. Plug them directly into a wall charger (5W or higher) instead of a computer USB port, since computer ports sometimes don’t deliver enough current. Leave them plugged in for at least 30 minutes, even if the indicator light doesn’t come on right away.

If that doesn’t bring them back, try a reset. Hold down both the power button and the volume down button together for about 15 seconds, then release. If the earbuds are still good, this forces a reboot and can sometimes bring back a dead unit.

If you still see no charging light and no response, it may be a deeper battery failure or a fault with the charging circuitry. At that point, I’d suggest contacting Apple Support or visiting an Apple Store for diagnostics—especially if they’re still under warranty.

Ref: Beats Repair & Service - Apple Support

Would you like me to also give you a couple of DIY checks (like testing the cable/charger with another device or inspecting the USB-C port for debris) before you head to Apple?