Your Prophet X is a several thousand dollar brick, useless.

Sequential Prophet X Brick Fix Tutorial

Rarely, but occasionally installing a new OS on the Sequential Prophet X will ‘brick’ the synthesizer. In other words it will freeze or crash, and will not reboot to a usable state. In this state nothing is functional and you cannot even reload the OS.

Do not despair however. Fortunately, you can boot the PX in bootloader mode and install a SysEx version of the OS, reboot and then reinstall the newest OS.

Important: The PX must be connected to your computer via the MIDI DIN IN port with standard MIDI cables and an Interface. You cannot use USB.

Bootloader OS: PX_Main_-2.2.0.syx

1. Boot the Prophet X into bootloader mode: Hold SAMPLE STRETCH while powering on the instrument. The screen will display a message indicating that bootloader mode is active.
2. Next, transmit the SysEX update file to the synth via the synth’s MIDI DIN IN port. Once the transmission has been started, you will see the Prophet X’s screen update to indicate the file’s reception.
3. Once the update is complete, restart the synth. The synth should boot up normally thereafter.
4. At this point, it is important to reattempt the OS update using the .bin file through the thumb drive. This will confirm that both the DSP and Main OS versions are up to date.​
5. Note: Sometimes on the 1st attempt, this update does not fully install. Probably due to flaky data conditions that caused the brick, the SysEx transfer could partially transfer and/or you may see snowy, flashing or blank screens upon final boot. Do not be alarmed, if this is the case, repeat 1-4.

The above instructions assume you know how to send SysEx files with MIDI-OX (Windows) or SysExLibrarian (MacOS). If you need SysEx instructions, see this page: Prophet X SysEx File Transfers.

So far, we have seen 100% success with this fix, but if it doesn’t work for you, contact Sequential’s excellent support department.

Thanks!
-Yehuda