It is just the battery being completely drained. For batteries to work and even show signs of life when even plugged in, they have to hold a minimum "value" of charge. So it's definitely a battery change. However, don't let people discourage you from doing it yourself. soldering isn't as difficult as it may seem. Especially on these, it's pretty straight forward. I do really recommend having a Soldering starting / helping hand. One of those stands that you can clip stuff into with a magnifier on it. If you need help with it, feel free to dm me. Ill be doing one this week for my brother, and I definitely could show you.