Once you get some new growth showing, or the old growth not dying off, she should be on her way, and will give more shoots than you'll need. (depending on your situation, lol) At this point, she might make it, might not. Don't give up on her though. As it says in my sig...your disappointments grow in direct proportion to your expectations. In other words...don't expect it to survive, but be happy if it does.

Likely not a good idea with the heating pad or blanket, unless they're rated for underwater use. (overspills, splashes...) Don't burn your house down.

Here's some very handy info regarding seedling mats and such...
Seedling Heat Mats and Inexpensive Alternatives

Some use a 24/0 lighting schedule in the growth phase for the heat benefits. Can't get away with this in flower though.

Is she showing anything positive yet?