holding down agressive, angry puppy

Question
12 month old Akita/German Shepard mix: kennel rescued from woods.
I tried your advised technique of holding down my overly agitated puppy when she gets upset over her leash. I pin her down by the scruff of the neck like a dominant dog would do to her when she acts up. Today I tried both hands, front and back. Her eyes roll back, she flails on the ground trying to extricate herself from my pinning down. She grunts, tries to growl. So I wait for her to calm down. I have tried growling a loud "NO!" at her. After a while, letting her up (because I am worried that she is NOT getting any better, but just angrier and flailing wildly on the ground and grunting), she rises from her submissive position upset, and tries to bite me. Now whenever she sees my hand coming along to extricate her leash (she hates leashes) leg entanglement she goes for a bite at my fingers and also my fist back of the hand upwards to simulate another dog.
Can you help me with this otherwise sweet puppy who gets in a snit over her leash and me trying to help her un-entangle herself? I am a calm person and quite working on showing her who is in charge. Though this issue of fighting with her, has her growling at me, ears laid back, she's just so upset and biting and nipping all the while she got all tangled anyway herself. She has never had anyone else ever walk her on a leash, and has to  learn to accept it. Really she is so upset at being pinned down that one can see her just plotting her revenge when she gets up! By the way, the way she flails about you'd think she was being hurt by a mean human being!

Answer
Poor thing. Since she was rescued, it sounds like she experienced some very traumatic events before you found her. Holding her down is triggering her to freak out like she was abused before you found her. She will have to be approached in a different manner. She will have to learn to deal with the leash & that's that. When she starts to get scared, just go down to her level & hold your hands out calmly saying her name. Let her continue to fail without any restraint until she calms down. Just stay at her level & calmly repeat her name & reassure her that it's ok. Then untangle her legs. Reassure her with hugs & positive words. She just has to learn to calm down. She has to learn trust & feel safe with you over her. I have a Dane that was abused & this technique was the only thing that worked on her. Please let me know if there's anything I can do more to help!
-Heather