Maybe tests have indents and evaporation lines that can be seen more once the test is opened. These types of lines do not require HCG to be seen. Plenty of people also open digitals then think they are pregnant as they see lines they wouldn’t see if they hadn’t opened it.
If you need to pull a test apart and are STILL wondering if it’s positive or not I would assume negative and test again the next day.
I mean yes, a very clear obvious positive result would still show a very positive clear result once opened. But opening a test that you think, might, maybe, possibly, kind of have a line, could well look more “positive” once opened.
And, if going by what the OP said here, the line isn’t in the viewing window so she could only see that line once it was opened. So I would not class that test as positive. Whether you want to call it invalid or whatever, the fact it was taken apart means it cannot be trusted to be a line if the OP could in fact not see it when it was whole.
So in my opinion, any test that has been ripped apart I would not trust whatever you want to call it. No one with a very obvious positive test would be ripping a test open and then questioning it.