there are two ways,
the simplest:
flash your phone with only one file! .rc2 in low or mid version
it works perfectly with z400 since it's qualcomm, too
it should work here
.rc2 contains only starting picture so should be no problems of any phone data loss,
the telephone formats filesystem only when you flash it with .ffs and it's different from previous .ffs file!
there should be another way, as i wrote you shuld get to the admin menu, however, i've got no idea how to do it in f480,
in old qualcomm phones [eg. z400 that i have] you entered admin menu by typing *#3695147*# or any *#******x*# code [diff operss have diff codes] and then you could do many things, eg. change debug levels, change speaker volume etc.. but to do some things you needed two more codes one for accesing "internals" function another one to set "pre configuration"
when i was making z400 firmware mod i changed all of the codes to *#00*#
hovewer it's impossible to do that in new qualcomm phones because the company have changed system of compressing the files if there was anyone to find a way to decompress new rc1 rc2 and ffs files i could do a f480 mod too,
admin codes used to be stored in *.rc1 in admin.rsr file but no acces without proper decompiling/decompressing and compressing it correctly again
@xxpoohxx
no there is no way to do a backup on qualcomm phone, at least there was no way with any model up to z400 or l760, you can do a memory dump though, but in a way it's useless cos you can't extract the files from it since they are unpacked, and to flash you need packed files
regards