That's what I pretty much thought but didn't want to make any assumptions.
I have several suggestions for you if this little one makes it:
1. First, be a little careful about a heating pad since they can cause thermal burns even on low settings. I'd fill a bottle with hot water, wrap it in a towel and put it in a box so the kitten can snuggle up next to it for warmth if necessary. You can also put a bag of rice in a microwave and warm it up and do the same thing but just closely monitor that the rice isn't scorching hot.
2. Gently clean off the wounds with very dilute over the counter Betadine or Iodine (to the color of weak tea).
3. You could apply a small amount of antibiotic ointment to the wounds since it's not likely that this little one will be able to lick it off (which might cause gastrointestinal upset).
4. A perfect product for skin lesions of this sort will be Vetericyn Spray which is available at many pet/grain stores or online.
5. As to care of the kitten in terms of feeding and stimulating feces/urine and husbandry, there are a number of excellent articles on the internet about care of orphaned kittens (which essentially this is). The following is one such article which contains a wealth of information.. much more than I can possibly provide here...although I don't necessarily agree with their advice about use of a heating pad! LINK
While taking care of abandoned or orphaned kittens can be exceptionally rewarding, I should warn you that there may be a reason why the mom has rejected her. In some cases, they can sense that their offspring aren't going to survive (for any number of reasons) and they don't waste what they consider their valuable resources (milk and nurturing) on them.
I very much hope that this isn't the case but I did want to prepare you for the fact that the kitten may not make it despite your very best efforts.
I hope this helps and that this little one makes it. Deb