Default unknown os stuck in bootloader

i have a photon that is stuck at bootloader and i dont no what os it has, i successfully unlocked gsm on 2 other photon with this:
http://forum.xda-developers.com/show....php?t=2058665, but i knew they were on 2.3.5, but this phone i have no info, should i search for 2.3.5 and flash that, and then start the above process, if its still on 2.3.4 will this be an issue, any feedback would be greatly appreciated