How to install Windows Mobile 10 on my Lumia 640 LTE

I have in my possession a Lumia 640LTE from MetroPCS and I would like to get it Window Mobile 10. I’ve already unlocked it from MetroPCS (got the unlock code and put in a non-MetroPCS SIM and entered the code).

I’ve been going through the forums and I can’t quite determine the best method to go about this? That is also the easiest, sure fire way (no bricking). The only thing I have done so far is use WPInternals to unlock the boot loader, and I’ve tried to put “RM1073_02166.00000.15084.41001_RETAIL_prod_signed _1005_01DE1D_000-CA.ffu” on, but it fails via WPInternals.