Mate , you must keep a "secret".
Work also without diod.
The secret is when you change Sim after flash , phone must be ON
BR
Another secret : Flash Phone with patched firmware. Insert 3 sim card , power On phone, insert code *854#46 (only 890) , phone restart automaticly.
Quickly you must change original 3 Sim card with another sim (phone dont turn off). Done.
Is not a definitiv unlock this one, but is first step. Any time you want to change sim card or Phone turn Off, you must do all from 1 step.
Best regards
Techgsmnet