Can't Revert to 5.0.2 after 6.0.1

I have a G920W8 and can't seem to downgrade after OTA update from Bell. I've tried running Odin with the stock 5.0.2 Bell firmware but i get this

<ID:0/004> Added!!
<OSM> Enter CS for MD5..
<OSM> Check MD5.. Do not unplug the cable..
<OSM> Please wait..
<OSM> G920W8VLU1AOCC_G920W8OYA1AOCC_G920W8VLU1AOCC_HOME. tar.md5 is valid.
<OSM> Checking MD5 finished Sucessfully..
<OSM> Leave CS..
<ID:0/004> Odin engine v(ID:3.1005)..
<ID:0/004> File analysis..
<ID:0/004> SetupConnection..
<ID:0/004> Initialzation..
<ID:0/004> Get PIT for mapping..
<ID:0/004> Firmware update start..
<ID:0/004> SingleDownload.
<ID:0/004> sboot.bin
<ID:0/004> NAND Write Start!!
<ID:0/004> FAIL!
<ID:0/004>
<ID:0/004> Complete(Write) operation failed.
<OSM> All threads completed. (succeed 0 / failed 1)

Just looking to go back to normal after an inverted axis problem. Right now my phone is unusable and can't use the *#2663# code as I'm on XtreS ROM.

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