That is such a scary, disheartening and guilt-inducing experience! You want your baby to be safe and she doesn't have the ability to discern that for herself in all cases.
You know, there are some things that children (and adults for that matter) just can't learn by being told. Meaning how would you have any idea what "hot" means if you never felt it? KWIM? I'm not advocating that all children need to be burned by a hot stove to learn this at all though! Just that telling a child no when they are curious is not very effective (as those little buggars demonstrate repeatedly).
My suggestion for you particularly at her age when reason and logic is only at the VERY beginning of development, is that you offer distractions - snacks, books, toys, other activities or whatever to draw her attention away from whatever it is you don't want her to do. We also use descriptive words to communicate instead of just NO. "Danger" "Hot" "Ouch" etc sometimes gets the point across more clearly than an emphatic NO.
Something else I've also learned in my parenting is that there are times when my dd is going to keep working at something until she figures it out. I do set limits for safety - but I ask myself why I don't want her doing whatever it is. Such as she's climbing on the back of the couch. I don't want her to do this because she could fall off, she could think that every couch is for climbing (thus alienating us from people who disagree), if someone is sitting on the couch and she's climbing it could be irritating or dangerous for them both etc. On the other hand, she's developing her balance, agility, muscles and brain and learning her physical limits, practicing a skill, having fun and entertaining herself in a semi-safe way. So - I can either fight the battle of preventing her from climbing on the couch continually for a few weeks, I can allow her full freedom to explore this and deal with any owies that come from it (and likely diffuse the interest naturally), I can talk to her about why I'm concerned and/or I can talk to her about climbing on the couch under certain circumstances.
Does that example make sense? Saying no, IME, simply increases the interest because the child already thinks it must be something REALLY neat and if they are prevented from exploring it, the appeal is all the greater. lol!
Books - "The Successful Child", "Everyday Blessings", booklet "Raising Children Compassionately"
http://www.cnvc.org
Hopefully you've gotten some support and ideas for how you might choose to handle this frustration...because it doesn't go away very quickly.
Take care, and keep us posted on how things are going!
~Amy