Not sure which Bolt model you have? Refer to this article.
If you've accidentally changed the video output format setting on your Bolt 300 or Bolt 500 RX to a resolution not supported by your monitor and you can no longer see the OSD to change settings, you can reset it to factory settings with the following steps:
1. power on the Bolt 300 / 500 RX
2. press and hold in the Menu button for approximately 5 seconds until all four wireless signal strength LEDs start blinking in unison, then release the Menu button
3. the Bolt RX will automatically reboot itself, and will be set to the default "Same as Input" option for the HDMI and SDI video output format
NOTE: This only applies to 2nd generation Bolt 300 RX units, it does not apply to 1st generation Bolt Standard or Bolt Pro RX units.