Photon RGB LED does not turn on at all even in Safe mode

[IOTrav]

You might take a look at this post and give it a shot to recover the Photon:

Dim D7 LED and no other lights

If you have another device (Core/Photon/P1/Electron) you could try this - https://github.com/m-mcgowan/embedded-swd It’s still in beta but it can be used to revive devices. This will try to fix things so that you can get into DFU mode.