You are lucky, because i succeed today to flashed back the new bootloader. one month ago, i made a wrong flash, and i destroied the bootloader. i was allways able to flash KK, but no longer Lollipop or Mashmallow.
so, if you dont' see the new TA with Emma, here is the way i did it this morning !
I dont' know why, but the problem is with the newest versions of Emma! i reinstalled the Emma V6 (fortunately, i have always the old archive), and what a surprise to see the two services : the last firmware AND the new TA.
As it's an old version, Emma failed to load the update, but it's not a problem. i ran Emma V6, tried to flash the TA, but it failed too.
so, before closing Emma, i went to the Emma\db\279242523\blob_fs folder and found three files. i decryped these 3 files with Flashtool and bundle a simple ftf, with only the new TA and the loader.
I flashed this new ftf with Flashtool, and that's it ; i have recovered the good new bootloader : 1274-7024 S1_Boot_MSM8x26_LA1.0_1027 !
for the time beeing, i just flash a Marshallow build and i am waiting for the boot process, in order to test it
and as i'm a good boy, you can find the ftf to flash with flashtool in the rar joined. Enjoy!