PID is usually written on the back sticker under battery.
examples:
8050D-HD Refresh (new camera, 2nd generation preloader) :
8050D-2[X=E,F,G,H,J]ALAPL , 8050D-2[X=E,F,G,H,J]ALMYL
8050D(4/5/6) (HD) (old camera, 2nd generation preloader) :
8050D-2[X=A,B,C,D]ALBD4 , 8050D-2[X=A,B,C,D]ALGB4
8050D qHD (first in line model, old preloader, incompatible with previous 2) :
8050D-2[X=A,B,C,D]ALGB1 , 8050D-2[X=A,B,C,D]ALIE1
check which one you have ..
First two have interchangeable ROM's, but if you flash 8050D-HD Refresh with 8050D(4/5/6) (HD),
camera will be only 8MP, instead of 13MP.
(but phone will power on and work..)
Last one don't have compatible rom/preloader with first two.
In any case, you should try using OTU Updater, since no rom packages are available on support.
Phone is serviceable only via service-center access, with phone in hands.
(or with same generation working phone, to read backup and write in malfunctioned one).
***** EDIT :
I found on Russian forum, backup from 2017 and 2016 model rom's :
2017 Model ROM - HERE
2017 Model ROM, for TWRP custom recovery : HERE
2016 Model ROM - HERE
TWRP Recovery - OneTouch PIXI 4 (6) 3G 8050D : HERE
p.s. ROM from post #2 is PID: 8050D-2BALAV1 ,
and is first generation, you guys probably have newer ones.
Check PID, and flash new model ROM's, Should get them back to life.
b.r.
Alex