It's just heart breaking isn't it? Sam sat in the corner of the kitchen for 3 days when we adopted her. NOTHING (cheese, hot dogs, chicken, apples, carrots, liver, peanut better, etc) would make her move from that corner. We leashed her and did the butt towel trick to get her in and out of the house. I slept on the couch in the living room (was able to hear her tags jingle) and that's the only way that we knew she was drinking the water.
So we ignored her for the most part - making certain she had food and water, talking softly to her whenever we were in her sight and gentle touching (which she always ducked like we were going to beat her). Took her approximately a month and an operation before she willingly started to come out of "her corner". To this day (9 years later), if a strange adult pets her she ducks. She never goes beyond the living room. She is much more comfortable outside where she can run from the "boogies" but will readily come in the house for DH, DS, DDIL or I. The only toy she will play with is a tug rope - no balls, stuffies, bones. Granddogs have a mother load of dogs toys because I keep trying. Everyone and everthing else is suspect.
She sounds like Sam - more flight than fight. While it is less nerve wracking, it's just as frustrating.
Hopefully she's just stressed with the situation and will come around quickly.
Sorry - that's all I have.