Reg- The sticky button thing is a great place to start- it has caused a lot of grief to Solo owners. I don't think the battery is a factor.
When landing, you need to hold the left stick full "down" until the motors stop. If you don't, the motors will speed up again. Of course, when using the RTL button, no stick input is necessary. Solo should land and shut off automatically.
I did a lot of flying with Solo this past week. After reading about landing issues, I decided to let Solo RTL and land completely.
I had no problems at all. Solo returned to within a few feet of its take off location. When it reached about 15' above ground, it slowed its descent rate noticeably and landed very softly.
(Using iPad mini 3)