Zte Zxv10 B820ca15 Fix -

Keep holding until the appears on your TV.

Firmware upgrades can often resolve issues with the ZTE ZXV10 B820CA15. Here's how to upgrade the firmware: zte zxv10 b820ca15 fix

If the ONT becomes unresponsive after a bad update, you can force a firmware flash: Keep holding until the appears on your TV