Dismantle Sennheiser ew500 - Sennheiser 100/500 G2 Series Wireless Combo Kit EW150ENGG2C Microphone

SOURCE: On/off button fell off Sennheiser wireless mic

This is quite common with G2's, and really annoying!
If you are lucky, 50% of the time the red button is pushed inside the mic.
You need to remove the bottom section:
- open the battery compartment
- there should be 3 star-bit screws around the outside (remove)
- pull the bottom of the mic off

If the red button is not inside, they are available as a spare part from Sennheiser dealers.

Be carefull when putting the mic back together, it needs to line up correctly with the internal guides, forcing the base back on could damage the ribbon cable. when the line-up is correct it slides on very easily.

Best of luck.
PTB