How do you test whether the battery is full or not damaged when the phone won’t open? My phone is a Samsung Galaxy Tab 2 10.1.
I'm guessing your Tab is really dead and won't take a charge. Chances are it isn't the battery that's the issue. I would begin troubleshooting with the charging cable. I understand that the cable is proprietary to Samsung.
You may be able to test for continuity using a multimeter with one lead on a point at the end that goes into your USB port or wall and the other lead probing the points on the Samsung end.
Or buy/borrow another cable and try that.
If the cable is fine, you may have an issue with the charging port or battery. Either way, you'd have to pop the Tab open and test in there with your multimeter, maybe order some parts, or take it to someone to be serviced.
If you're willing to open it, check out the tutorial at IFixIt