This is such a difficult story to read. The pressure on this teacher this year will have been terrible and a huge punishment for what happened. I have enormous sympathy for her and I'm glad that she has stayed in teaching and stayed alive.
I agree that the teacher made mistakes, not just in paperwork (for example in the situation where a group of children took out the glue guns when told not to use them I wouldn't have let them get away with that, just because the not following instructions thing would have made me assess it as too risky if I was supervising different locations). But this is what happens in highly stressed situations. People make bad judgements because they're trying to juggle lots of priorities and in this case more than one set of safeguarding priorities.
The school has failed as well. It should have had a blanket glue gun risk assessment ( you shouldn't have to write your own every time just adapt it), and when the child refuses to show the injury or go to medical or run cold water on the burn there should have been some process to support that behavioural challenge. I think the immediate pressure to resign for not filling the accident report was appalling and am surprised the teacher didn't contact her Union. Yes, a warning perhaps, yes a school reassessment of why things were getting so pressured but you don't just dump a good teacher for a single error after an unblemished career. You try and find solutions. Shame on the trust for running scared of the Sun.
I could see that at home time the teacher might have felt it impossible to keep the child and better to let them go home. When dealing with a non compliant child she could well have thought that keeping them back would have caused a problem (I am sure there would have been a complaint, as someone up thread said she would have been in trouble also had she neglected her other duties to call).
Time is the problem, and teachers picking up too much. With more time or support she could have called the parent or delegated it, or delegated gate duty perhaps. Safeguarding issues would have derailed her thoughts and I can understand how she could have forgotten to call home immediately. Friday night? I'm guessing she was exhausted.
All in all, she admitted she made a bad mistake, and fell down from best practice. She's clearly a dedicated and experienced teacher. She didn't deserve a petition to remove her from school. In her place I'm not sure I'd have been able to go back to another school... no wonder we're losing teachers so fast.